Chevy & GMC Vans

I was driving up the sea to sky highway today, up a steep hill, at full throttle for about 20 seconds, and then experienced loss of power and flashing MIL. The problem didn't come back, and the light eventually went out on the trip back. It's no biggy, but a sign that something is probably on its way out. I later scanned it to be P0304: Cylinder #4 Misfire Detected. I know there's a number things that can cause this, but where would you guys start diagnosing? Ignition components?
Cheers.

First step is pull the plug and check the colour and condition. Then check the leads for burns cracking or possible grounding on the block or dog house cover. If all that is good then check the cap and rotor. If that's good then put in better gas and stop speeding on the sea to sky or you will get a ticket that place is crawling with cops. Even if you don't see the cops they often run the RCMP helicopter to catch the bikers speeding to whistler.

Kh pretty much covered it. One thing to check is the play in the distributor shaft. I replaced the distributor in the "Smilie" van because the bushings were warn. It caused a misfire.

My driving record is very good, KH. I was passing on a steep hill. Thanks for your concern and tips. I will report back.

Just didn't want to see you go to jail or get the old girl towed

Never thought about slop in the distributor. My sister had that happen once on a old toyota corrola she owned with like 300 000 km on it.