tranmission

:xmy jeep wouldn't go over 30mph and it would rpm between 4,000-5,000 and i had found it had been the speed sensor, i replaced it 2 months ago and havn't had a problem since until last night it started doing it again so what could be causing that????? any help would be great

Forgot to add these parts to my messed up hard top post. Got a dana 20 transfer case, T-150 3 speed (1976 -1979 CJ5 4.2L 6 cylinder) they were both working when pulled (last year). Also have a TJ (1997 - 2002) convertible soft top with soft upper doors complete with all hardware. Make me a...