TxSheriff

having some idle issues on my truck that i have been having hell figuring out what it could be.
**everything i have done or mechanic has done***
new-fuel pump, fuel lines, fuel filter, spark plugs, distributor, Idle air control valve (IAC), bleeder hose, air filter.


i have replaced all these parts/ or they have been professionally installed by a mechanic and we still cant figure out what exactly it is.
the mechanic suggested i try here for help before we replace anything else so i dont waste any more money guessing the problem.

**problem**
while starting the truck, the idle stays at 2000 rpms, and when i place the vehicle in drive, i dont have to press the gas, the truck accelerates on its own, one day i clocked it at 33mph all on its own with out me pressing the gas.

any help would be greatly appreciated
Nick C