my 88 460 starts good and runs good for about 20 min to 1\2 hour then it starts to miss and idle rough. the only thing i know that acts up after warm up is the ignition coil. can you guys think of anything else?

 

I May have asked you this before, are you running a closed loop system with an O2 sensor and a map sensor?
Are we talking about your jeep that you have in your siniture or something else?
How does it act above idle?
Jimmy

 

yes, it is the jeep in the sig. and yes it has both the map and oxy sensor. it has a miss above idle as well. really noticable at light throttle say at 25 mpg and slowly climbing.

 

It almost sounds like an ignition miss. I am thinking possibly the pick-up coil in the dizzy?
No cats to be clogging?
It could be a weak coil breaking down or even an ignition module doing the same.
Usually, the module will just quit though.
I would try the coil first, it's the cheapest.
Jimmy

 

i think it sound like an ignition miss too. it is similar to when the plug wire leaks. the rotor cap module and wires have been replaced recently but i think the coil is a good guess but i have noticed that the muffler is discolored some believe that this discoloration is caused by a blockage. maybe one of the cats puked into the muffler and obstructed it. i will keep tinkering with it and thanks again for you help.