Fitech wont rev under load
I have a 600 hp 2x4 on a 455 Oldswith dual quad high rise offenhauser . Bought it last year in July. Had it running in August and ran great . External fuel pump, distributor is locked no vacuum. Unit has pwm. Car has been running with no issues till the other day. Car revs perfectly fine to rev limiter on msd unit. Sounds great. Problem is when I drive the car, it bogs and goes almost dead at around 3000 to 3500 rims at 1/4 throttle or more. Basically stepping on gas and car just bogs and won't accelerate at all. As in not a bog , just plainly does nothing, just a dead space and sounds dead. When I let off gas it goes to running fine again. I can do 70 easy on freeway just don't go over 3500ish So it's not msd , coil or spark issues. Revs fine with no load ,only driving issues. Map sensor, fuel pump pwm , possible a clogged fuel filter somewhere ( revs fine in park ) ? Thoughts, opionions ?
I used to run fuel filters with the "stainless screens". When the engine got warm - the screens would "expand" restricting fuel. Switched to high-end Aeromotive cartridge filters. Solved my issue immediately.