why would car run a half hour then stall on 1991 Buick Skylark

runs fine awhile then it just stalls have to let it set about 15 minutes then it will run fine for a few then stall again

Asked by for the 1991 Buick Skylark
3 answers
number #1 is correct, does the vehicle fire back up immeditly or do you have to let cool
Im having same problem. Research is telling me its either crankshaft or head gasket. Let me know which one you do/did and if it worked
My guess is a defective crankshaft sensor.