the xj has a new radiaor new themostat (didnt even have one when i got it)new water pump and both fans work new hoses also you have to start it in low gear then get it into high when you take off the front sinks down it over heat after like 20 mintues and it wont get over 2000 rpms please help those are all the things going wrong

I don't really understand what you're saying, but from what I can make out, it sounds like you may have a clogged cat converter.

It over heats after like 20 minutes and really doesn't have power like its suppose to while driving won't get over 2000 rpms

Also pulled it home yesterday behind the f250 I was not pressing three brake in the xj the whole time but when we got back home the right front brake was smoking like crazy

Well now it sounds like you have a siezed caliper on the right front.

Can that holds down the rpms and cause it not to pull right?

If the caliper was locked up it should still rev up but would not pull very well. I'd check the converter, start it up and let it run and check and see if the converter is really hot and the exhaust after the converter is alot cooler.

Old rubber brake lines tend to come apart internally, they close off and will not allow pressure to release causing the caliper to drag.
One way to check this is when its dragging, open the bleeder valve and see if there is built up pressure (it will squirt out) .
If so replace the rubber line, bleed the brakes and go on. Fixed.

Id say you have two problems? check your brake master cylinder pushrod adjustment, you didnt mention any recent work on your brakes, could be a sticking caliper pin, also sounds like a restricted exaust flow? good luck and post your fix, riper1.

I think I know about why the brake is holding but it still won't get over 2k rpms or pull right in drive but if its in park it revs normal?

This may sound stupid but do you have it in 4wd if so if you have 2 different size tires this will cause your front to dive and work the engine harder.

No the 4wd light does come on at random times and the brake light on the side is on unless I'm pressing the break

I checked the compression its good so don't think its a head what those could it be?

ok i stuck the jeep up on jacks the tires would barely turn. so i cleaned of the cailbers really good. now it seems to be doing better in the front but still wnt get over 2000 rpms in drive and ideas????

HELP