we swapped to an 88 harness and ecu, same stuff though it runs better then the 91 stuff did. all the wiring into the truck is correct. ive checked it over several times now. the 88 harness and ecu worked perfect in my 84 supra. pulled it out when i installed the megasquirt stuff. weve swapped out every sensor and whatnot with KNOWN GOOD things and it does the same stuff. engine is rebuilt and perfect. only thing im not sure on is his maf, injectors, and maybe the fuel lines, but the popping at 2k wouldnt be fuel lines. no load or boost to have a high demand on fuel. i didnt think about it but i guess we could try adding a couple 4 awg grounds from the block/head to the body. might help since the battery is in the bed of the truck.