Car Help?

[MagicHef]

I know there are some knowledgeable car guys on here, and maybe someone can help. My 2001 MR2 Spyder has been running really rough, and I've been running in circles trying to fix it. The previous owner installed an aftermarket turbo with custom headers and exhaust, K&N intake, piggyback ECU, anti-knock system, and higher flow injectors. I've had it for 5 years and it has been working well until recently, so I don't know that the issues are directly related to any of the modifications.

So far I have replaced the fuel pump, fuel filter, fuel pressure regulator, fuel injectors, coils, spark plugs, camshaft sensor, crankshaft sensor, MAF sensor, and O2 sensors.

It was simply running poorly (sounded like it had a dead cylinder) and not throwing codes, but after replacing the camshaft sensor it started giving codes again. Now it gives codes for misfires on all 4 cylinders, plus random misfires, and says the system is too lean.

I am about out of ideas and hoping that I'm overlooking something obvious.