I have a 99 TL and at start up it vibrates for about 5-10 seconds hard then it presumes its normal state. Could it be that I need a new motor mount?

 

IAC valve may be sticking, try cleaning it out

 

does the idle fluctuate during this? Probably the mounts.

 

i recently had this problem as well..but my car would idle very low and just turn off and I would have to restart the car again. it happened only once and I dont know what it is. i know its not the motor mount cause I recently had it changed at the local dealership.

 

Clean your IAC valve

 

what's an IAC valve?

EDIT: found out what it is, now WHERE is it?

 

No, the idle doesn't fluctuate. Just a hard vibration for about 10 seconds. If it did fluctuate what would that mean?

 

i got the same problem.

it will also vibrate sometimes when the rpm drops below 700

 

I think Ive got this problem too anyone have a DIY? or can anyone take a picture of where I can find the IAC valve?