Need help troubleshooting inexplicable/erratic stalls 2001 RT190P Chev

[1phatred]

An Oldie, but a novice re: the above stated issue.
These stalls happen seemingly without causative factors...i.e.
1. Drive smoothly into a campsite; park for a few days; on anticipated departure will fire up readily, but stall repeatedly unless I 'feather ' the gas pedal; but once on the highway, she'll right herself and run smoothly..(until the next time!) Was advised to use SeaFoam then which seemed to assist in re-starting.
2. Can have driven without issue for 3+ hours at highway speeds. Stop to let dog out to stretch his legs and my rig won't start. Let her sit for20-40 minutes and she'll fire up again; only to stall at a stop sign 2 hours later and repeat the (non-)performance. Once again, SeaFoam to the rescue. I now
keep SeaFoam in the rig always against the next time. Have been told to remove the gas cap for a minute or so, then replace it...this trick doesn't reliably work.
When the old girl (the RoadTrek, not only me!) throws these 'snits' I have no power, no brakes, no steering, no NOTHING...which is very frightening...especially whilst in a crowded parking lot exiting a sloping parking spot and trying to avoid 'kissing' a brand new Jaguar!
I have a brand new battery...she'll fire up and run smoothly, and I don't let the gas drop below 1/2 tank...but at this stage, I have zero confidence she'll stop throwing her little 'snits'.
What's the best advice as to where to start looking to resolve the issue, PLEASE. I am BAFFLED and FRUSTRATED!!!
Thanks in advance for any/all suggestions from you folks with more experience.

[mkguitar]

hmm I just replaced the fuel pressure regulator on my 2001 GMC sierra 4.8L
( same motor series) the regulator is on the driver's side of the intake. if you pull the hose off, if there is any gas at all- it needs replaced.
( amazon $15 but you may need to swap in the GM O ring- I did)


a fuel pressure test is easy to do on these. should be about 52PSI and hold pressure for 15 or 20 minutes with motor off.

I dunno if cdn tire has test gauges, in the US harbor freight has a $30 set


my main symptom was easy starts when cold, yet hard starts ( long cranking) when hot-
this was because of raw gas leaking into the intake through the regulator when motor first turned off...essentially flooding it



which is a different symptom than yours, but similar




as far as "feathering" the throttle- I may need to do this if the battery has been disconnected ( which I may do to avoid drain when parked for a long period )
the ECM has to 're-learn" to maintain idle speed which takes some time and cycles of on/off



I experience this both with the 2001 GMC and the 2005 Chev van used for my Pleasure Way


either of these sound plausible ?


have you checked the ecm for any stored codes ?


a fuel pump issue ( unlike regulator) may show as pinging on hard acceleration ( followed by loss of pulling power as the ecm retards timing ) and/or as a lean condition code in BOTH banks stored
and as above, a pressure test on the fuel rail will reveal...



mike

[booster]

As Mike said for possibles but add possible fuel pump. Since this appears to be idle related, maybe best to start there. The symptoms you list could very easily be a sticky or failing idle air motor, which regulates the air to the engine at idle and also anticipates idle and throttle off and sets for them also. Could be as easy as a loose or damage connector on the idle air motor.


Idle air motors are cheap and pretty easy to change on most GM products as they are right on the throttle body at the front of the engine.

[1phatred]

Thanks SO much for your input. I plan to c/p the replies I get and bring them all to my most trusted mechanic. Only issue with him/him reliable work, is that his small, very-small-town garage doesn't have enough headroom for a hoist to lift up my ~9ft high RT. Otherwise, this guy/his operation is a REAL GEM!
So, with the suggestions on this forum,(for which I am truly appreciative!) he might be able to explore & determine which issue is the culprit without lifting her up. Thanks again to any/all responders!

[mkguitar]

the aspects mentioned above are all done at ground level, lifting the hood


and/or plugging into the OBD port above your parking brake
mike

[KurtFranz]

This may seem unlikely, but it could be the fuel filter. I had similar symptoms as these many years ago in my RX7 and I went nuts trying to figure it out. Installed a new one and good to go.

Something to possibly consider

[1phatred]

This is a 'blanket note of appreciation' to all who have/will contribute suggestions to resolve my stall issue in case I miss sending an individual one. I'm very willing to pass on every suggestion to my mechanic. As you've no doubt guessed, I am completely frazzled by this and not thinking straight. His, and your patience is commendable. Thanks again!

[krgracia]

Just because something similar happened to a few days ago: sparkplugs were very fouled (they were due for change out in August) and a throttle gasket replacement. I had it run horrible in town, great on highway speeds of 65 mph, just did not want to start up in the morning (took me an hour once to get it going), and overall unreliable as to whether I would be able to take off after parking it at grocery store/campground. Although I was a couple of months away from maintenance, the plugs were just corroded beyond what my last change out was and the mech said they are seeing more of that due to less quality gas lately although I use Shell, Chevron, and Union 76 (I guess some gas station somewhere is watering down their fuel.

[Austinrt]

We had somewhat similar problems with our 1995 Dodge Roadtrek Popular. It turned out to be that we needed a new distributor cap and rotor. As with the other suggestions, checking this does not require the RV to be lifted.