Knocking/Missing after warming up

[94/Z28]

My 94 Z28 only has 47,000 miles on it. After running for 10 or 15 minutes it starts to miss and knock badly. i can still drive it, but i can barely give in any gas. I know this could be an opti-spark problem, i just wanted to ask if there is anything else that could be causing this.

Thanks for everyones time.

[Morley]

Without a scanner hooked to it you are just shooting in the dark.
The cheapest part to replace that could cause that problem is the 02 sensor.

[94/Z28]

ok thanks morley. Anyone else have any other suggestions?

[greyrealsteam]

hmm... bad distributor, something with spark plugs or wires or cap and rotor. possibly MAF sensor. theres lots of things