I need some help..any advice would be helpful

I have an 03 lightning boosting about 15psi on the stock supercharger and the other day it started sputtering at wot..i changed plugs and it stopped for a bit but as soon as i got into wot it started doing it again and know it got worse..i changed plugs (ive tried NGK, autolite, Motorcraft) and tried different gaps and it kept doing it..so i changed all coils and cleaned injectors..and it is still doing it..it only does it at wot over 5psi

Please help me out?

 

Fuel pressure?

 

Have you checked fuel pressure?

 

Im actually going to do that tomorrow...it has two 255 walbro in the tank..what should be the pressure? is it the same at idle and at wot??

 

I'm not sure with dual pumps. But my stock pump puts out 58-59 psi @ idle & drops to around 56-57 psi @ wot. When my old pump started to go out it still would show 58-59psi @ idle, but @ wot it was around the 43psi range.

 

its not a fuel pressure problem. when you changed plugs you likely didnt set the gap on all of the plugs to .030-.035" stick with NGK TR-6 plugs.

 

Sounds like spark blow out to me

 

Timing ??

 

Or this

 

+1 probably running stock gap that the plugs came with