I have put about 900 miles on a new 385 with s-trim 7psi, For the first 700 miles or so everthing was fine, Now the car runs great for about 10 miles and then after that if you give it any throttle it stutters and hesitates. You can reach higher rpms but it's missing the whole time, The more throttle you give it the worse it gets. You can turn the car off and let it sit for 10 minutes or so and it won't miss but will start missing in a mile or so. I had a fairly new opti (3000 miles) but replaced it and vented it , I have tried a new MAF, Coil, Ignition Module and checked everything I can think of. I tried running in speed density but still the same miss. It's not throwing any codes and the only thing I can say is it always does it after being warmed up (closed loop). Is there any sensors or anything else that would go bad after the car is at operating temp? The only thing I noticed differewnt in my datamaster files was that my AC pressure before this problem was at 70 or so and now its 140. Thanks for any help in advance.

 

Check 02's?

What are your BLM's at? Reprogram as a test forcing the car to stay in open loop only and see what happens.

Ben