2000_5.0.e55

Hi, I recently got a 2000 e55 AMG. I was told the engine was shot and causing it to misfire and say it has low oil though it doesn’t. I picked up an engine from a 1999 sl500 with 64k miles and got it installed over the weekend. This is my first time doing anything like this but the only thing I could think of is when I switched the wiring harness from the AMG motor to the 5.0, I didn’t change the intake manifold gaskets after undoing it to get to those two sensors. Everything went good, but im having an issue with misfiring. The car turns on and idles good around 500 rpm. If I try and rev it lags a little bit sometimes and I can only press the pedal so much before it starts to bog down. It cuts power just after 2k rpm when it’s cold and 3k rpm when it’s warmed up. If I don’t gas it the misfire is on cylinder 5 and 7. If I do gas it sometimes goes to 5,6,7, and 8. I’m not sure what could be causing this. I’m only getting codes for misfires.
Here’s what I’ve tried:
checking fuel pressure at idle. About 55-60.
disconnected the MAF and tried turning it on (my brother told me to give it a shot but it just turned on and bogged down.)
I’ve checked the vacuum lines ( a few were bad so I replaced them, some are slightly cracked but I’m not sure if they are bad. )
I also had the ecu tuned for the 5.0 ( still has stock amg ecu and wiring harness)
compression is good
I’m stuck here and tried looking for something like this but haven’t figured out what the cause could be. I appreciate any help.
I might’ve missed a few things, and I did not change the gaskets when I changed the harness since I couldn’t afford em atm. Will replace them though.