Hello, I recently purchased a project car a 94 sn 95 with 197,000 miles on it (it is bone stock the previous owner had it since it was new never did anything to it) In the beginning it wouldn't rev up past 2000 but there was a problem with the cats so I removed the inside of the cats and welded them back. But since I fixed that problem it struggles to rev up under load when I am going on a highway. It feels like it wants to go but it just struggles at wot. I already replaced spark plugs, cap and rotor, coil, mass airflow sensor, o2 sensors, fuel filter, and some suspension parts. It definitely made it run way smoother. I pulled off the codes and the only one I found was 553 which is Air management circuit 2 failure. Please help!