i have just recently bought a 1991 2.6l magna when the car is in drive the car shutters quite bad but it will only do it in drive and i have noticed that the revs will sit at 500rpm this car has recently had a new head and a reco alternator i rang mitsubishi and they said it need a idle reset is that true or are they just wanting to make some dollars? my other problem is a fuel problem i can drive for 1 hour on the highway and use about half a tank in petrol is this right? i have a theroy its either the o2 sensor or the computer that runs the efi system let me kno your thoughts thanks

Welcome man.
For the idling problem, i would probably suggest your idle speed controller (ISC). From memory it is about $100 to have it replaced. For fuel consumption, o2 sensor is a common problem...but it's like asking how long a piece of string is. There are far too many variables at hand.
In the future, do a search and see what you can turn up, these are common problems and there's a wealth of information within these forums.
Enjoy your stay!!

Hi there and welcome to the club.

Sounds exactly like what was happening to mine. it runs like a pig? Getyourself a timing light, a size twelve spanner and adjust the distributer cap until you get idle of about 950+ or - 50 RPM in park or neutral. It should be fine after that though.

they said it need a idle reset is that true or are they just wanting to make some dollars?Getting them to reset the idle shouldn't cost much at all, personally I don't know much about the idle control on the 4cyl, but this would probably be a first step rather than going straight out and replacing the ISC. Might just need the base idle speed brought up.

As for economy, without usage figures it's hard to say exactly how bad it is, but as a very vague observation yeah that doesn't sound right. Should be more like "2-3hrs".

Could be your idle that needs adjusting, which can be adjusted simply by turning a screw. OR it could be masking another problem, such as the ISC on it's way out.