Ignition retard only at WOT

Truck is a 1990 M/T with a 3.4 swap. Originally it came to me with a 2003 Tacoma A/T wire harness and ecu. Issue with the truck was that it felt “gutless” on WOT.

After test driving I confirmed that ignition timing goes 15-20 retarded on WOT and you are unable to go past ~4,000 rpm.

After messing with the wire harness for the automatic ecu for a few days I decided drive by wire was my issue and it would be best to swap the ecu and wire harness for a non-drive by wire.

After a lot of effort the truck now has a 98 M/T 5vzfe ecm, wire harness, and throttle body. Yet it continues to have the same issue at WOT.

I’m honestly at a loss at what else to check. Oil is clean, plugs are new, coil packs and wires new, almost every single sensor has been replaced with OEM, valve clearances are within spec, everything wire harness wise is fine. Still having timing go 15-20 degrees retarded every time you attempt WOT. Timing is spot on. The only thing I can think of is that either it’s having spark knock or there is actually something wrong with the bottom end of the motor. Only CEL code is for Evap pressure sensor due to one not existing. Does anyone have any input?

 

Also worth mentioning, motor has been changed 3 times.
Original donor 3.4 was seized.
2nd 3.4 had a socket stuck in a valve
3rd 3.4 came with blown heads and was machined, slight tapping can be heard at idle on this motor.

Fuel tank had rust, so filter and pump have both been changed 3 times.

 

Also compression test is almost 200 psi on all cylinders

 

Have you changed the crank position sensor, we've seen this issue before without it presenting a crank position code.

 

Crank and cam position sensor have both been replaced with oem sensors

 

After two weeks wasting my on this I finally figured it out… backwards fuel filter