a friend of mine has a 96 hyundai accent and it wont go over like 55 mph and feels like something is draging it down. it wants to shift downwhen you drive faster. a belt did break and fall off and it happend to be the belt for the alternator and water pump. it did go up all the way to hot but it was shut off immediately. got a new belt and it started up and aint for sure if the problem started right after or not because it was driven cautiously back to house it was a day prior to the problem that it got hot. think maybe head gasket is bad? or even separated? it does run ok just no power real boggy...

 

Do a compression test, that will tell if you have a serious problem or not.

If I had to guess I would say you blew a head gasket or warped the heads or something.

 

well i did a compression test and they're all running about 130. the engine seems to run fine, it starts up perfect, but it wont accelerate fast. if you slowly accelerate it will bild up to speed. i check the exhaust to see if it was plugged up and even when i run it with just the exhaust manifold it does the same. also has a k&n filter on it. i change most of the sensors on it and computer but still nothing. i changed the head gasket too.