Young Stallion

5.4liter from a 99 f-250 swapped into a 2000 gt mustang. The car stall out after about 10-15 minutes of driving and usually starts back up the first try. Now sometimes it may not even happen all day but other times after driving for a while it'll stall out more and more. Gets to the point of not starting back up unless you wait awhile or relieve pressure on the fuel rail. The other night though it just wasnt starting even though I was relieving pressure. So waited like 20 minutes and it cranked over.

-I replaced the fuel pump (stock for gt mustangs) and fuel filter when I first got it thinking that was it. Turned out it wasn't.
-Has 30 lb injectors that may not even be tuned for it
-I bought a pair of 19lb injectors and put them in but it didn't want to stay alive. Found a old chip on it called autologic so i pulled it reset the computer by disconnecting the battery and still did not want to stay alive with the 19lb injectors. It Does stay alive with the 30lb injectors whether the chip is plugged or not.
-Has a 4.6liter intake with the adaptor plates for the 5.4l
-BBK 70 mm throttle body
-Accel coils
-New spark plugs
- New SR performance black cold air intake.
-Stock maf sensor for gt. Turned out it had a v6 maf when I got it. Runs better now.
-90,000 miles on car and approximately 15,000 on motor.

Any other thoughts as to why it stalls with everything listed above with 5.4 swapped. Also shouldn't it be able to run with 19lb injectors even after resetting computer with or without the Autologic chip on it.

school boy

Remove the accel coils and replace them with motorcraft. People have had trouble from them quite often.