I have an 88 MJ with a 5 speed. I was having intermittent high idle problems for a long time, about 2200 RPMs and the only way that I could fix it was to unplug the IAC. I have replaced the IAC with a new unit but it made the idle problem worse (possible bad new unit). I am also having a bucking issue that seems to happen above 2000 RPMs, especially when maintaining speed or lightly accelerating. The bucking happens regardless of how the truck idles. I know that I should fix the ICA issue but that shouldn’t be causing the bucking. Not having an IAC should really only affect the truck when cold at start up, correct?
I have done the following:
Replaced and adjusted the TPS
Replaced the CPS
Cleaned and added grounds
Cleaned the C101 connector
Replaced plugs, wires, cap and rotor
Replaced the fuel filter and checked fuel pressure
The only things left that I think could possibly be causing the bucking problem would be a bad O2 sensor or a faulty EGR.
I have done the following:
Replaced and adjusted the TPS
Replaced the CPS
Cleaned and added grounds
Cleaned the C101 connector
Replaced plugs, wires, cap and rotor
Replaced the fuel filter and checked fuel pressure
The only things left that I think could possibly be causing the bucking problem would be a bad O2 sensor or a faulty EGR.