04 VW Jetta 2.0 manual not going over 3000rpm

Possible plugged up catalytic converter.

From research of reading other forms I've heard a few say that replacing the MAF fixed the problem. Should I check that first before servicing the CAT?

That is up to you. A MAF should be cheaper than the cat but a back pressure test on the cat is where I would start.

If the pressure is low or insufficient is there a way to clean/fix the CAT rather than replace it??

You could try a cat cleaner or snake oil. Not much difference in my opinion but if you can spare $10 go for it.

BTW - if the pressure is high the cat is bad. Low is good.

Haha, alright. Thanks for the suggestions. I'll try em tomorrow and return with an update. Hopefully a solution too..

So I unhooked the battery for 30min as suggested to reset the computer and get it out of limp mode. Upon hooking up the battery the car won't start. It seems like the fuel pump isn't coming on now.

Turns out I fucked up the motor. Wen't to replace the belts and didn't get the TDC right. Locked up the motor n froze it.. What other size motors besides the 2.0 will fit in my 04 VW Jetta??