88 GT Standard……replaced fuel filter, and IAC valve. Cleaned the throttle body. That pretty much took care of the crazy idle hunting; however the idle is still wavering between 900-1000 RPMs. Also slight lag or hesitation when accelerating through 3500 RPMs.
You might want to pull your distributor cap and inspect the rotor and inner terminals. If you plug wires are original they may be breaking down from age. Also check all your rubber vacuum lines and connections to see if any are dry rotted or split.
I think its the coil. I replaced the distributor and rotor, wires and plugs and still had this problem. It would lag at certain speed and and almost seem to hesitate at times. Looks like the new coil fixed the issue
[This message has been edited by marc-alan (edited 07-06-2014).]