Jeep Strokers

hello! I've been using this forum to build my stroker and now am a part of it!
I built a 4.6 stroker block is machined .030 over, using comp cams 68-235-4 cam (210int/218exh), icon forged pistons (IC945-030 10.8cc), stock intake for now, 24lb injectors@49psi, 50 psi regulator, im sure im missing a detail or two but hopefully that narrows it down enough to help with my problem.

Sitting on my driveway the engine runs great, once I upgraded to the 50psi regulator it runs like it should, revs fine and doesn't make any noises. Under load however (typically quick acceleration) It sounds to me like its backfiring out the exhaust. I can feel it in my gas pedal foot sometimes. I did have some check engine lights (obd1) but they were all sensors that I didn't have or weren't plugged in. I have since corrected that and there is no longer any codes

I posted a video in all things comanche on Facebook and they said it sounds like a cracked flexplate but in my opinion after watching other videos specifically nickintimes video about it and checking the flexplate with a pry bar and it seemed to be solid.

Im wondering if I should be worried about this being detonation or if I choose maybe the wrong size cam, wrong size injectors, o or something else that isn't good or maybe its just my intake is too small and its not getting enough air?. Just hoping to get some other perspectives and hopefully a solution

Its really only confusing me because it only happens under load.

Pic of my longblock right after paint.

Did you try indexing the distributor?

Yes ive tried indexing it with no luck, also just put new plugs /wires in today and it didn't help im running out of things to try that aren't related to the internals of the engine. What confuses me the most is its only under load in the driveway it runs amazing, should I try swaping in a different ecm? Ive got a parts cherokee I can use

It could be something as simple as a header leak.

Are you sure the timing isn't retarded. Try driving it again. Get it warmed up. Go get it backfiring. Get out and look at the exhaust . If it is glowing red then you most likely have the timing retarded or a lean condition.

What are your spark plug gaps? Too wide will cause misfire under loaded conditions. Weak coil will do the same thing.