Buick/Olds: computer problem, crankshaft position sensor, injector pulse

Question
1990 BUICK CENTURY 3.3
205,000 MILES
I AM HAVING SOME TROUBLE WITH MY CAR. THE PROBLEM OCCUUED SUDDENLY. THE CAR STARTS AND RUNS FINE UNTILL ABOUT 15-20 MINUTES INTO TEH DRIVE, THEN IT SHUTS OFF. AFTER ABOUT 5-10 MIN WAIT IT FIRES RIGHT BACK UP. THEN AFTER ANOTHER SHORT DRIVE IT SHUTS DOWN AGAIN. THEN IT REPEATS THE PROCESS. I FOUND THAT WHEN IT SHUTS OFF I LOSS SPARK.I GOT 3 CODES FROM THE COMPOUTER-CODES_ 26,27,28. I HOPE YOU CAN HELP. THANK YOU.

Answer
You also need to check to see if you are loosing injector pulse. You can unplug any one of the injectors and use a test light or a 194 sidemarker bulb to jump across the 2 connector terminals. It should flash when cranking or running. Try it while it is running to make sure you are doing it right.
If you are loosing spark AND injector pulse, the problem is probably the crankshaft position sensor breaking down due to heat.
If you are ONLY loosing spark, it is probably the ignition module.