My 1991 Volvo Turbo 940 recently is having trouble starting up, but only while still warmed up. It starts up fine first thing in the morning, but if I start it within 2 hours or so of shutting it down it will turn off if I don’t keep my foot pressing the gas peddle. Then it runs fine, with no idling or stalling problemn. This doesn’t happen every time, but often enough that it is a concern. The “check engine” light comes on sometimes, but not always.
Someone with a little mechanical ability can read the trouble codes for the check engine light. The instructions for doing it may be at www.autozone.com under Emissions Controls & Driveability. The spark plugs and wires should have been renewed within the last couple of years. The Engine Coolant Temperature Sensor is a suspect. If it’s lying to the computer, the computer won’t know it (no polygraph). == me_art12