Well this been going on for a few days. The car starts fine and runs fine. Then when it gets hot it will start missfiring really bad, barely will run, (sometimes the SES light will come on sometimes it won't.) And then without doing anything to it just keep driving it will straighten up and run fine? It done something similar to this before and I changed plugs and it fixed it. But the SES light never came on and it done all the time. Anybody ever had this happen? Could it be something simple? I'm thinking probably optijunk.

 

When I took out my LT4KM and put the LT1KM back in....it cleared up all my problems. That's an easy thing to try.....

 

ok thanks I'll try that too, I changed plugs today and it has run good so far, still has little shake when idling though.

 

Had the same exact problem. Check the cable from the coil to the opti. When I pulled mine off it was all corroded (white powdery crud). May not be it but worth checking out.

 

Mine is doing the same thing except no codes. Im changing spark plugs and wires next week, if that doesnt work its on to coil, then optideath.