My 2001 toyota tacoma just had a timing belt replaced and i have notices when i am at a stop with the A/C on that my truck trys to lunge forward. Not to sure what is going on or if it is a cause of the newly put in timing belt. The truck runs fine with the A/C off. Automtic transmission and I know when it is about to happen now because the Rpm's drop to about 500 then rev up to about 1200. Frustrated and need some help Thanks!

 

Mine does this too, I thought it was just a change in load from the compressor clutch locking in.

 

Take it back to where the work was done and have them look at it.

Off the top of the head:
Make sure all the vacuum lines are firmly attached and electrical connections plugged in. Seems like some idle up control is not functioning properly.

http://www.ncttora.com/fsm/2003/Repa...c/trou/pst.pdf

 

thanks