Originally Posted by 99allgonoshow99 View Post
My 99 revs to about 1.5 2k right when i put it in drive or reverse drives idles normal after though sometimes it feels like its gonna stall when i stop. like if u tried to come to a stop in a 5-speed w/o hittin the cluch feels like the tourqe conv wont let go but i dont think there related. the motor is an 03 long block stock with the 99 upper intake an other acc. i also just sprung an evap/intake leak code but its been doing the revving gear thing since the swap. Thanks
One of the possible causes of slow idle especially when stopping is a lock up torque converter that is not releasing as it should.
One of the other causes of high idle is a vacuum leak after the throttle body. A leak in the intake manifold qualifies.
IMO, you should consider the possibility that the problems ARE related and the problem solution is right in your hand.
Does it have a delayed engagement in drive and reverse? What is the condtion of the fluid?
Regarding vacuum leaks, today's cars simply will not run right with even the smallest vacuum leak. I suspect that onced fixed, there will be a world of difference.
The link below has more information about how to troubleshoot IAC problems. In your case, it doesn't make sense to perform the steps as there is a known vacuum leak. https://www.allfordmustangs.com/forum...ml#post2260649