[storm9c1]

I agree with others, if trans was slipping, you hear the engine rev up but the truck won't accelerate. From your description, engine isn't even revving. So... let's reset.

What have you changed since the incident? Oil, spark plugs, timing. OK. Anything else?

Excess oil in the engine probably didn't hurt anything as long as you drained it and refilled it to the proper level since then. If the cylinders were washed out, you may need to burn it out of the cylinders, which should have happened with a few drives already. Did you pop off your PCV hoses and make sure they aren't full of oil? Otherwise there really isn't anything else that would worry me.

The spark plug change and timing change does concern me. What gap did you use on the new plugs? Do you have HEI? Did you make sure you didn't accidentally swap any plug wires? Recheck the firing order.

How did you check timing? Did you make sure vacuum advance was unhooked and plugged? What timing values did you end up on?