need help car not reving over 4000rpm

[D32]

ok here is my bad story my car ran fine and i bought a 3'' downpipe put the downpiple and i started driving it to the muffler shop to get rest of exhaust put on after driving for maybe 5 or 6 miles the car started redlining at 3k so i finally got it there i looked for intercooler pipes and vac line i couldnt find anything the next day i bring a trailer to pick it and the car ran fine no problems so i drove it all weekend and it started doing it agian so i took it to a shop and he found injector 4 was not work so i bought a pair of 450 sense my is a automatic after putting them in it took the misfire away and idled smooth but soon as i got to 3000k or so it would back fire and seem like it is redlineing there its is running very rich ### gas is coming out the straight 3'' piping i got so i bought safc2 and took it -15 across rpm for a start but it didnt effect the back firing at all so i did boost leak test found some fixed them after putting it back to gather i started it let it run and i happen to push on the cas plug and the car blew mpi fuse so i got a new one put it in and it runs alittle better after fixing booost leak put the plug for cas is alittle messed up but it still redlines at 4k and at idle check engiine light is on but soon as i hit gas light goes off im so confused im ready to give up on and also the afc2 is hooked up and work ### if i start to lean it back at idle it will start to shut off

 

[blktalonawd]

Make sure that the wiring for the CAS is not grounding out and throwing the CEL. ALso the computer itself needs checked, it could have leaking capacitors or burnt traces. The car is throwing fuel from an irregular airflow pattern. Check the maf connector and maf itself. All of these are major culprits. goodluck