Runs on 3 cylinders when cold

I have a 95 S-10. A couple days ago I started it up in the morning, runs on 3 cylinders. Get on the road, after about 10 minutes it starts running normal, misfires here and there. Same thing next day. The only thing I had done was the oil changed the day before this started happening. Checked for loose s/p wires, they seem ok. Fouled plugs? Any ideas?

Could be bad plugs, bad CPI unit, bad wires, bad cap and or rotor..

When my head gasket went and my head was cracked my truck ran on 3 out of the 4 cylinders, but it was definitely not as long as 10 minues, probably about 30 seconds. If my oil pressure guage is correct, everytime I change my oil the pressure is a bit higher for a few days (no, it doesn't leak), so maybe yours is the same way and your boost in oil pressure caused something to fail. Just a guess.

Check to see if you may have knocked any wires off of any sensors or maybe a vaccum line. start off simple. any codes??

I beleive the 95's were HEI weren't they?
I had a similar problem, ended up being the of the coil packs starting to fail.