stalling and stumbling

[juniorcarp]

I have posted this probelm before but i still have the probelm i have a 4.3lv6 1995 chev ck 1500 truck when i start the truck i turns over for about 5 - 10 secs it starts and sometimes will stall again ..... it starts up and the choke picks up when i start driving alls well but when i drive about a block and come to a light it idles up and down not to bad it sometimes will stall when i accelarate it stumbles and backfires then stalls (also it shift horribly holding at a gear and not going down till i let off the gas )it will start again all this goes away once i have driven it and warmed it up to normal temperature it will hesistate though and shift rough .... i have chagned all the usual braindead things plugs cap rotor wires i cleaned the egr and i am at my wits end is it the fuel pump and filter my carb does someone have any idea

[Crasen]

it sounds like an IAC valve, dirty or malfunctioning, are you saying it has a carb, because it originally came Fuel injected. Does the check engine light come on? have you checked fuel pressure?

[Rs051802]

I would ckeck the filter. The pump you should be able to hear turning on and off. Check the map sensor as well. Whenever you shift does it idle up after the clutch has been pushed in? I have a 95 4.3 my original motor did that some. Have you check for a vacuum leak around the intake and tbi. Both those gaskets leak often. Keep us posted, we can figure it out.