also, I'd replace the cover, line the pulleys up right to verify for sure your belt jumped, and go from there. the super rough running engine sounds like it could have jumped a tooth. if it was more than one tooth it would probably have bent valves and not even start.
try to wiggle the main crank pulley though or examine the rubber between it in the actual pulley. if thats all ok then that probably isnt the problem.
reason I say this is because it could be something stupid like a spark plug wire arcing or a plug thats fouled out.