Interesting note, I met someone at our local Sports Car Club meeting last night who is having the exact same problem except he's using a Haltech F7A. Interesting...

 

f7a? old school! i'm still thinking its a fuel/vs engine temp issue, i'm thinking its the ecu map too.

 

My 8 had a similar issue running a microtech unit... it would run/idle great when cold... but when temps got up..it wouldnt hold an idle or start up... adjustments made to the coolant temp vs "primer" as j9 called it fixe the issue... i believe the microtech and the haltech are similar in nature as to how they treat that issue.. so i dunno how to explain in on the MS system..never used it..

 

Alright, I've got a set of 720's I picked up from my parts storage that only have 700 miles on them. I'm going to give them a try and see if that fixes the issues, since all of the 550's I have seem to be giving me major troubles. (none of them have a good spray pattern)