Engine Light

Ok so a few weeks ago I had a random misfire code (P0300) I changed out the plugs and cords and put some cleaner into the tank and got the engine light to go off. (The spark plugs were cheap, I knew they wouldn't last long.)
I have driven some 600+ miles in the past 2 weeks, and my engine light is back with more (P0300) but also (P2610) it says Control Module not programed or ECM Failure...
The (P0300) has me wondering maybe it is the plugs and could the ECM be a short? I am not much of a mechanic... I can do minor work. I can't afford to take it in, the dealer wants some $80 just to diagnose it. I think its usually like $80 per hour that's not including parts. I just purchased my car 6 months ago, I have already put about $1,000 into it. Any insight would be helpful.