Rough Idle only in Drive/2/1 or Reverse

91foxbodymlx · 08-03-2008

I have a 91 Mustang where in Park or Neutral it idles smooth, but once i put it into gear (drive or reverse), it dips low and idles rough, till the point where the car starts to shake. Thanks in advance guys!

93slowpony · 08-03-2008

your idle may be set to low, what do the rpms look like when its in park?

91foxbodymlx · 08-03-2008

in park its about 500-600 rpms, then when i put it into drive, it dips lower to about 300 or so and then the car starts to shake

thanks bro for any help!

MackDagger · 08-04-2008

Check Vacuum pump hoses. Had this problem with my 93 2.3 it would start and idle fine but when i would shift to drive or reverse it would die. Hose clamps fixed my prob.

NavySVO · 08-04-2008

At a warm engine condition, you should be idling at 900-1000 RPM. Bump it up and bee what happens.

91foxbodymlx · 08-04-2008

i bumped up the idle to about 800. It now idles fine in drive and reverse for now. Thanks a sh** load fellas!