All the parts mentioned have less than 50 miles on them with the exception of the transmission but it doesnt grind or leak so it's good for now. I've checked the fuel relay and the fuses with a test light and there's been no red flags there. Computer grounds are properly done and dont seem To have ever been touched vacuum lines are all good and proper. I initially assumed mechanical failure because it abruptly stopped working after giving consistent behavior for two days while I drove it with varying degrees of hardness. It idled high but steadily and started strongly. Every replacement part is OEM spec as I was told it was a stock car so I've been operating off that assumption. I know the cats are shot because before the fuel pump and transmission were replaced it shot fire out of the left tailpipe and not in a safe way. Would be sometimes small sometimes so violent I could feel it in my chest. Also forgot to mention when I had it running for a little bit the other day there was a small amount of white smoke coming from the throttle body and possibly a small amount from the same tailpipe that shot fire. Also inside of the throttle body after taking off the air filter I noticed a black substance which I assumed was oil but I didnt check to be sure as I was just spraying it with starter fluid and trying to solve its other issues but that may very well be part of it. If I've got a blown head gasket I do luckily have replacement gaskets for everything.