What would make the engine cut out under a load on a 1990 Oldsmobile 88 Royale?
From my unfortunate experience and the amount of information I gathered on the subject, two sources of faults can make your engine cut out under load (I assume it is not a diesel engine): ignition or fueling. Ignition: if the spark is "weak", it will be smothered when the engine is under load, giving poor or no combustion. Main reason for this would be bad High Tension leads or ignition coil primarily, or too big a gap in spark plugs. Fueling: A clogged filter or an ageing/dying fuel pump would allow the engine to idle or rev freely under no load, but as soon as you are asking for some power from the engine it would just die. In both cases, the engine may seem to be running perfectly OK when not under load. Hope this helps.