1994 Mustang 5.0L auto 117K miles. Total stock. New fuel pump, fuel filter, distributor, timing chain and gears, balancer. Set timing at 10 and it runs strong up to 3800r.p.m. then it starts sputtering and backfires (exhaust) but only under full throtle. It don't do it when normal exceleration just when you punch it. Have new coil to put on but don't want to keep going in that direction until I get some feedback from you all. Thanks for you help any questions please post and i will answer if I can.

 

Have you checked the FP? Sounds like a lean condition whether fuel or spark. May aso wanna maybe swap out the distributor with a known good one to be sure it isnt the module

 

You try pulling any stored codes, yet?

 

I see you put a distributor in it....new or used? If new...I'd lean toward fuel or timing. Double check the firing order. Lean usually will make it backfire through exhaust and tomong through the intake......leaning towards fuel.

 

I would almost put money on the dizzy

 

So did I thats why it has a new one(dizzy). Timing is dead nuts! No codes other then EGR. Fuel pressure is at 42

 

oh well so much for internet repair lol.long time no see you should swing by the shop sometime

 

Try cleaning the mass air double or nothin lol

 

lol, Thanks John I will do that in the am. Yes I should drop by

 

did you look in the tank for depris or rust?
I had one that was doing the same thing and it was in the tank.
sounds like a fuel problem to me,pump could be bad also even though it's new