Fueling & Injection - Problems with new set-up....NEED HELP

Cars specs:
370
texas Giant
92/92
underdrive 25%
Ram Prowergrip HD
38 lbs injectors
Walbro 255lph pump
Patriot Stage 2 heads
All major bolt ons minus a EWP
Still on driveabilty tune- Tuned by Local Shop (have yet to get on it:()


Alright, here's the deal. I just put in a 370, about 2k ago. Now that we have the Texas heat going on here the car is acting up. In the morining the car runs great, however when I come outta work and try to leave( hottest part of the day) the car will run for about 5-15 minutes, it will then start missing and idling lower and lower till it dies... the car will start again and run for 20 seconds- 1 minute and be missing until it dies again. Pumping the gas, or holding the pedal to the floor while cranking doesn't help to start it. This has happened while actually moving a few times but mostly at when I come to a stop. Car's temps never get crazy, so it can't be over heating.

I have replaced or tested the following things

Plugs-NGK TR55
Wires-MSD's
Coils

Voltage was with in spec when they were hot/cold

TPS
IAC
MAP- Brand New
IAT- Brand New
MAF
Tested for open circuits/ ground connections
I have also tested the fuel pressure and it stays at 55-50 psi, however when I attach the tester I get pressurized air in the line before the fuel comes out. I'm not sure if this is normal...


Need some ideas before I push it off a cliff!!!!! :mad::bang::mad:

Could be a fuel tank venting issue, perhaps the tank is building up too much pressure while sitting in the heat all day through expansion of the fuel and that is causing a vapor lock situation. It would explain the air in the line when you put the gauge on too.

Check you gas gap maybe get a new one, if it has evap, check those lines too.

repalced gas cap, and something I forgot to mention is everytime I put gas in the car will be fie but will throw a code the next run cycle code P0442 small evap leak can't figure it out for the life of me... I clear it and it doesn't come back till I fill up again..

So in this situation I could test it by purging the fuel rail, and also opening the gas cap then going to see if it will start after I relieved the preasure???

amyone else have anything or other ideas???