Increasingly difficult to start eventually wearing down battery...

[Taxi]

I have a 2003 Stock Ranger, 4cyl., about 50,000 miles. After a rough start and some white smoke (fuel in the exhaust) I put in a full can of C-Foam to clean out the tank and injectors as I'm pretty sure I got a bad batch of gas from the local quickie-mart gas station. Since then, over a period of about two to three weeks the vehicle seems to take increasingly longer and longer to start, then eventually kills the battery. When I recharge the battery it is not severely drained, just down enough to not turn over. My Battery charger is not showing a fault with the alternator (but its a basic charger so that doesn't mean all that much). I don't have any rough starts anymore, and no more white puffs of smoke out the exhaust so I think I cleared out the injectors and gas situation, but still wearing the battery down. Not getting any check engine lights or anything either so I don't think its throwing out any codes. Battery, Starter, Alternator? Just looking for some advice on where to start, I don't want to buy a new alternator if I just need a battery, or starter.

 

[MAKG]

White smoke isn't fuel. That's black, and it fouls spark plugs dry-black.

Truly white smoke is either coolant or ATF.