1991 Chev GMT 400 6 cyl stall out issues

[Jeremy N Meagan Gardner]

I have a 1991 Chev GMT 400 6cyl.  It has approximately 175,000 miles on it . I recently have put  a new starter ,water pump , fuel pump ,and battery in it within the past 2 weeks. Plugs, wires , and distributor cap and throttle ppsition sensor (i believe thats what its called) was changed about 2 yrs ago. However ,I've been having an ongoing issue with it that has been there since I purchased it and I can't figure it out. Whenever my truck is in idle it will sputter and stall out. It will sometimes sputter and stall in park . when I change it from park to drive, it will sputter and stall out every time. When I'm in drive and I come to a stop it will sputter and stall out ,unless I press the gas pedal too then it will stay running. Also when I'm in reverse and stopped it sputters and stalls out.  Also I noticed if I'm in park and its running fine ,when I cut my wheel as far as it will go ,that will cause it to sputter and stall out. But like I said in park its very iffy , sometimes it'll run OK and sometimes it'll stutter and stall out. Other than that the truck runs fine as far as driving it goes  and this sputtering and stalling out is the one issue I cannot figure out! I'm hoping someone out there knows what it is BC I have no idea and I'm hoping it'll be a quick ,easy and above all cheap fix . I bought the truck in 2017 and it had this issue , and it did sit for 2 yrs ,BC I used my car to get back and forth to work.  But I believe I cracked or blew a head gasket in my car so I know that's gonna be an expensive fix. So after sitting for 2 years I decided to fix whatever it needed so I could get to work. And the things I had to replace within the past 2 weeks was the starter, water pump, fuel pump ,and battery. And also new tires . so hopefully I have given enough info to help y'all figure out what it could be . thank u for taking the time to read this and for your knowledge that you give to help me out. I'm not a mechanic ,so if you can , please be very specific on answers so that way I can know for sure what you are talking about . thank you!

[Jsdirt]

Without being there in person to see exactly what it's doing, and testing things, I can only give you a WAG (wild-assed guess).

 

If it were mine, I would clean the throttle body all around the butterfly of built up carbon. If that didn't change anything, I'd test the throttle position sensor for proper function - the fact it was replaced recently makes that instantly suspect to me. EGR function would also be suspect - if it's leaking at idle, this will cause stalling.  Last on the list would be removal, testing, and cleaning of the idle air control valve, Injector spray pattern (with timing light), and a fuel pressure check.