I have a 1993 gmc sierra. I have been have

Assuming it is in the distributor,
you remove two screws & unplug the wire
connector

Try using heat sink grease between the metal base of the ignition module and the mounting position, from the sounds of it the circuitry is overheating and failing. I noticed that this particular module is very hot while the truck is running with my own Sierra

When you turn the ingnition switch to start can you hear the fuel pump humming?

i have a 1993 suburban gmc 1500. when i put the key in an turn it nothing happen at all.befor the car stop running it use to act crazy like start up in run great but when u turn it off it dont start back up. u wll have to wait than it will start..can u tell me what that can be..

Make and Model: Chevrolet Suburban, GMC Yukon XL, Chevrolet Silverado, GMC Trucks Sierra
Years: 2000-01, 1999-00

Turn the ignition key to the RUN position. Fully push and release the accelerator pedal 3 times within 5 seconds. If the CHANGE OIL SOON light flashes 2 times, the system is reset. However, if the light comes on and stays on for 5 seconds, the system did not reset. Repeat the procedure if the system does not reset.

Hope this help (remember rated and comment this help) Good luck.

fuel pump in gas tank turn igniton to run position and
listen for fuel pump in tank sometimes if you hit the
tank with a rubber mallet in the middle vehical will
start

any engine codes? could be the throttle position sensor

check the switch on the emergency brake pedal may need an adjustment or may need to be replaced

Hardly seems worth changing the lock cylinder, since it is not that easy.
Just be more careful turning the ignition off.
Put in an ignition indicator light on the dash if you have to.

You are gonna need a New Ignition. Will solve this Problem.