i have a 1990 rx7 that i just bought...it has a rebuilt engine, with an upgraded turbo, intercooler, blowoff valve, stage 2 clutch, and probly other stuff i don't even know about...it runs good most of the time but when i shift it makes a loud backfire and a flame shoots out the tailpipe, also...sometimes when i try to speed up fast it chokes. i don't know what it is...i don't know if it is helpful but it also has the power steering pump taken out since i've bought it and it has an apexi super air flow converter. someone help.

 

Blowing flames is a bonus... The hesitations, could be tons of stuff, start with a basic tuneup and work your way up from there.

 

backfiring, flame shooting, popping, etc.. comes along with a turbo rx7....

As said, start with a tune up. new plugs, wires, good tank of gas, etc...

 

yeah mine does that too....like when I floor it....sometimes it hesitates i guess...it makes this weird jerking when I step on the gas, what is that? throttle cable maybe?

 

Probably a grounding issue... When you floor it the 2ndary injectors kick in, they are opened and closed by the ECU gounding out the circut at blinding speed.. If the main ECU ground is not good then the Injectors do not transition smoothly creating a hesitation.

 

What are you controlling fuel with? Sounds like you could
possibly be dumping to much fuel in.