my car moves byitself in 1st gear

[honduraneclipse]

well ive done my basic tune up .... plugs wires oil change and filter air filter, fixed the exhaust leaks..... but my car moves byitself in 1st gear when my car is at high idle rpms( 2000rpms - 3000rpms)..... basically saying if i drive the car hard for a little while it starts to idle high.... when i give it gas it goes back to 1000 rpms but again it would go back up to high idle when im in traffic... the car is extremely loud and annoying....... side note : one night my car was idling very good at 850 rpms i decided to turn my MBC up just a little bit 5 seconds later my car starts to idle at 1500 rpms..... please you dsm tech heads please help me because i need to pass my state inspection soon it expires this month....

 

[peregrine]

pressure test the intake system.

 

[candela]

www.vfaq.com

 

[honduraneclipse]

i already checked that no conclusive answers

 

[BlkAWD]

I had a similar problem. Check the throttle cable to the throttle body. When you car is warm the cable expands and will open the throttle plate just enough to mess with the 'idle'. Just undo that cable bracket from the intake manifold and put a little more slack in the line.