Do the RPM's continue to rise at upper RPM's and the car doesn't really do anything? Bad clutch then... Here's how to check it (might sound funny, but it will work)... drive down the road at like 25-30 miles per hour... put the car in 4th gear... push in the clutch rev it way up in the RPM's like 6-8K then dump the clutch watching the tach... if the clutch is going bad, it'll slip.... if it not, the car will just get this boggish feel...

let us know what you've checked already so we can help fix it.. You say there is zero check engine lights correct?