Ok my LS has 123k on it, and when I start up the car, it idles fine, but when I go and try to accelerate and put a load on it, it hesitates badly and bucks really hard. after about 2-3 minutes the car drives fine. this happens every time I turn the car on. I am thinking the IACV, any other opinions?

 

three things could be wrong idle air control valve,tps sensor and vacuum leak.

 

Temp sensor to the computer. If it reads wrong, the engine is lean when cold, like a choke not closing on carbs. Vacuum leak also possible.