I have a 91 tracker that did the exact same thing. Turned out the ecm had a problem. (the ecms are made by mitsubishi and allways go bad eventually. a problem they later fixed) I found a guy on ebay that fixed mine, cost 70 bucks and came with a warranty. took out the ecm sent it to him got it back in about 10 days put it in and the car fired right up and i have not had a problem since and that was almost 3 years ago.
here is a link to his ebay page
http://cgi.ebay.com/ebaymotors/89-94...spagenameZWDVW
happy motoring