Typical, after it gets warm (10-15 min) it stumbles. So I replaced the spark plugs and the wires. It seemed to be fixed but wasn't. The spark plugs I put in were NKG Tr55. I was sure it was the opti, but I decided to change the gap on the spark plugs to .35 instead of .50. So I pulled the plugs out and they were gapped at .58! So now that I've gapped them to .35 there is no more stumble. I let it idle in 95 degree heat for 10 minutes, and then I took it for a 20 minute test drive. NO STUMBLE. I thought I would post this for all you guys out there. I know how frustrating it is.

Hope this helps someone,

Zack S.

PS I also replaced the coil and mounted it away from the block, replaced EGR valve.

 

god bless you!!! I will try this!
I am battling a stumble problem myself

 

Hey no problem. The reason I had the hesitation the first time was because my #7 plug wire was melted, and the platinum tips had fallen off the spark plugs. I just took it for another test drive this time like a 30 minute one, free way driving, in town and it did great! Hope this saves someone from buying an Opti! My Opti has 110k miles on it to!

Zack