idle stuck
 

so i cant lower my idle lower than 1500 and i need it at 750. a little while back i didn't start my car for about 6 months and it idled at 2500 so i lowered it to 1500, i think something is stuck but donno what. it is an manuel 84 celica supra

Have you looked at the ignition timing with a timing light? If it is high it could be the problem.

I would also consider checking the inside if the throttle body..Some times build up of crap will cause it to stick open more than normal causing a high idle..Im also seconding the timing mentioned before..