I have a 97 GMC Sierra k1500 with a 305 (5.0L) engine. It seems like every year for a few years now it will suddenly start missing very badly. There will be random misfires on all cylinders almost no power. The first time I replaced plugs, plug wires, distributor cap and rotor button and it fixed it. The last couple of times I think I only replaced the distributor cap and rotor button to fix it.
The other day it started again. I'm getting tired of doing this every year. Does anybody have an idea why this keeps happening? Is there a way I can diagnose what part of the ignition system is at fault without buying parts and swapping things out?
The last time I had it serviced the guy told me he thought my intake manifold gasket was leaking because he could see some oil on the front of the motor. I haven't noticed any oil or coolant leaks in my driveway. Its not smoking and I don't think my oil has any coolant in it. Given that, I don't feel like the intake gasket is related to my immediate problem or is it?