Recently I rebuilt my throttle body,replaced the idle air control valve. The engine ran fine for a week or so then i started having idling problems and stalling, and little bit of black smoke from exhaust. It stalls at every stop or sharp turn. It also stalls frequntly on the highway every 1 mile or so. The tp sensor has been replaced 4 months ago. Could it be the fuel pump? Please help !

 

Well, check your fuel pressure and see.
Also, getting any codes / check engine light?
Checked or changed your pcv valve lately?
What about your oxygen sensor?

 

It sounds more like a bad fuel pressure regulator. That or a bad TFI module. Check your fuel pressure. Check the spark. When was the last tune up done? I'm talking complete tune up, cap, rotor, wires, plugs, ICM and O2 sensor. If the truck has a lot of miles on it, and it's blowing black smoke (rich condition) it's toasted the o2 sensor. You'll have to fix the other problem BEFORE you replace the O2 sensor though, as if you just put a new one in first it will die in short order from the excess amount of gas in the exhaust stream.