would a 1999 2.0L turbo beetle engine fit in a 1998 jetta?

it should you might have to do a little custom work

If the Jetta is a 2.0 as well then it will work.

so i wont have to change the intake, exhaust or computer?

2.0 Turbo was not offered in the 99 Beetle....it's either a 1.8T or 1.9TDI or 2.0AEG... all 3 engines are different from the 2.0ABA in the 98 Jetta...manifolds, computers and possible wire harness changes are likely. Check out this FAQ: http://myweb.whitman.syr.edu/srotblat/swap/ It can be done...just do your research. And join a forum or two that deal specifically with your vehicle.