Please help car hasn't run right in months

[savage6]

Well here's the problem, I can get in the car, crank it up and it runs fine. Idles well, no SES light, no smoke, nothin'. When it gets warm (140+) it starts missing during any accelleration sometimes to the point of cutting off. Here's the weird part, if it starts missing and I cut it off or it dies, when I crank it up again,(42) SES light comes on and it stops missing, kind of like it goes into a bypass mode or something drives fine but has no power when i go WOT.

Any ideas?

 

[suicide six]

Try the easy things first,Maf swap, not an aftermarket unit,a known good one,a loner if need be.Coil pack or module,Make sure chip is seated good.A spare ECM comes in handy now.Make sure your GRDS are good and tight.Loose belt pulley,failing cam sensor.Cooked plug wire or failing ones.Vac leaks.What is your scans showing before dying?

 

[savage6]

Well the car has new plugs gapped at 34, wires, coil, module, ls1 maf with trans+, chip is seated fine, ran a new wire from ecm to ignition module(white/ black stripe), all changed after the car started f'n up. I have had bad maf's before but when that happened the car would idle fine and run decent until boost, now the car runs fine until 15+psi when the SES light is on or before the car is warm. it's set at ~20psi with no knock.

 

[Bescurred]

sounds like a bad module to me or maybe just maybe a crank sensor

 

[joeatgbody]

What About Timing Chain Or Compression Check, I Had A Cust That Was Doing The Same Thing And It Had A Hole In The No.2 Piston, But Oil Pressure Was Down Also, So Maybe Not?

 

[GNRick]

I see you have a Walbro, but maybe it's fuel pressure? My car is doing funny things when it is warm, like back firing. Also looses power at WOT. I put a fuel pressure gauge on it and found FP doesn't go past 42, even at 15 psi boost. I'll report back after new Walbro 340 install, hopefully this weekend.