my 91 legacy 2.2 engine runs great when in idle but when i put into gear it idles really low and shakes alot.

SOunds like you have a vaccum leak someplace. Have you fiddled with the engine recently?

 

 

nipper

The car's computer controls the idle via the idle air control valve. The valves can sometimes get sticky with carbon and not respond as smoothly as they should. You can squirt brake cleaner down in there. I would check for vacuum leaks and the normal stuff as well.

sorry to hijack, but where is the air control valve located? Specifically on my 93 impreza L? Thanks

Should be located in the same place as the first gen legacies

 

http://www.main.experiencetherave.com:8080/subaru/images/injectors/DCP_2470.JPG