I recently acquired a 1988 Chevy 2500 with the 350 tbi in it that has about 80k miles and had been sitting for a very long time. When I got the truck it had a miss fire, back fire, and very poor throttle response. Since getting it I replaced the fuel pump, leaking fuel lines, Idle air control valve, MAP sensor, EGR valve, both injectors are new(not reman), and new spark plugs. After replacing these the throttle response is working correctly and there’s no longer backfires at idle or on the gas. But when driving the truck to work and parking getting ready to turn the truck off it’ll start misfiring and essentially sounds like it has a cam in it, sometimes even completely shutting off. But 8/10 times if I shut it off and turn it back on it’ll stop doing it. it also idles high when warm and stopping at stop signs or stop lights it seems, but this could be I’m not used to driving a vehicle with this big of an engine considering I’ve been driving a ford escort for the previous two years but I had a 97 with spider injection and don’t recall it trying to pull away like this. I figured I got a faulty idle air control valve so I warrantied out the part and installed a new one and the morning after I went to start it wanted to idle rough, so I shut it off to restart it seeing if it would stop like it normally would and it just sat there and cranked. It only started when I gave it some throttle. I’m thinking on getting maybe a different brand idle air control valve to see if this would help but figured I’d ask to see if anyone has insight on what else would cause this