Tried to go out twice today - Merc 200 troubleshooting help!

[garbubba]

Tried to take the Son-in-law & Grandaughter out Friday, had everything ready, weather did not cooperate. Tried again this am. Get to the launch, back in, try to start, grrrr, nope. Knew the one battery was weak, had charged them both Thursday. didn't run it after that because I'd added the oil, but not the gas yet....

No biggie, pull out, tie stuff down, off to the auto parts store, new battery & bam!, back at the launch. Starts up, but rough, doesn't want to idle. Head out the channel & hit it and it doesn't want to go. Seems like a power pack, no power at all but smooth. Pull back to the dock, open it up, look for obvious anything, nope.

Back home, wasn't meant to be.

I can test the power packs while they are on the engine, right? Just dug the manual out.

assuming that's it, what's the best choice as a replacement, used parts, after market, or new Merc? Did this once before, can't remember what I used.

Thanks.