Contour Enthusiasts Group Archives Forums General Troubleshooting Light throtttle-induced bucking

Hey everybody,
I got my car back from the dealership last week with a rebuilt trans and new clutch. 3rd no longer grinds( ), and the clutch feels noticeably sharper, the wheels will now light up cleanly if I drop it at 3000RPM without any grinding or shudder.
But lifting my foot on or off the throttle quickly will induce some bucking through the drivetrain, and I am wondering if this is due to a dirty throttle body (or IAC) sticking at it opens or closes. The engine seems to run fine but exhibits the classic "moosing" noise when the A/C is on, and RPMS will occasionally drop and she will stall.
Secondaries are definitely working.

64,000, and it does need a UIM/LIM cleaning along with the throttle body and IAC replacement.

Check the motor mounts and roll restricters. Old ones could easily have been damaged when removing engine. Drivetrain slack including the C/V joints possible.

I'm having the same problem but it is when i'm driving for 30min. it does it in 5th gear and i can be heavy on the pedal and it will still buck. I have asked for help before and no one answered me if you could help it would be nice.

Well I doubt the motor mounts beacuse I don't notice this problem under a hard launch or fast cornering, etc, only when stabbing the throttle real quickly. I guess I was wondering if anyone knew if dirty TB or iac valve could cause this kind of symptom.