Have you or someone else messed with the idle mixture screw? If the cap is still over the screw then that shouldn't be your problem. If the cap is gone, its been messed with and prob needs to be reset. Idle mixture screw is right in the middle of the side of the carb. Its either above or below the little half moon hole.. if it has a cap it will be a full moon, if no cap there will be a screw instead. If you don't know what I'm talking about which I dont <img src="/forums/images/graemlins/lol.gif" alt="" />, I'll find a pic for you.

see here

Quote

Initial Idle Mixture Screw Adjustment

When assembling the carburetor, turn the idle mixture screw the number of turns specified below. After the carburetor is installed, perform the appropriate idle speed/mixture adjustment as detailed in Engine Performance and Tune-up .

22R:
*1982- 2 1/2 turns from fully closed
*1983-88- 4 turns from fully closed


Good luck,

Scerb

http://www.scerbfab.com/carb_faq.html