Any ideas?

1998 4.0L - Engine rpms drop to an idle while driving. After the vehicle is turned off and sits for 10 to 20 minutes the problem goes away. There is no consistency to this problem! No check engine light. Fuel pump, distributor, TPS, CAT., O2 sensor, have been replaced. Any ideas??

 

Might be the Ecm.

 

just my 2 cents -- clogged fuel filter? maybe not getting enough gas?

 

Is your throttle cabel still in one piece?

 

Has your catalytic converter been rattling?

I've seen the converter insert rattle for so long in the housing that it became a perfect sphere. When the sphere would find it's way to the pipe outlet while driving, it completely blocked the pipe and the engine would not rev.

 

check your throttle cable look for any binding or breaks

 

Cable is good

 

Converter has no rattle

 

Fuel filter has been replaced

 

clean the intake manifold and/or throttle body?

you never know...

any possibly loose wiring somewhere?

 

I have not cleaned the intake or throttle body.

All the wiring has been chased.