91 Volvo 240D waggon, 175k miles.

Several times the engine, when its been both warm and cold, shudders briefly and then quits. Starts right back up after turning the igniton off then back on. Lately its also been running a bit rough until it gets a little warme, then its OK. Currently the "check engine" light is on.

I took it to a Volvo mechanic after it died the first time, he said the fuel computer was acting up, but since the car was 11 years old they didnt recommend I spend over a grand on a new computer. They "checked the codes & reset" something, the waggon ran well for a month or so then quit again. These guys are honest and didn't charge me much so I know I wasnt getting ripped off or having BS thrown my way in an attempt to get me to spend money.

Any experts out there have any idea what might be happening? If I can troubleshoot/fix the problem myself I'd like to give it a try, I am mechanically inclined and have a Haynes manual which unfortunately doesnt seem to be much help.

Tnx,
Bill