The engine actually ran good for me all the time, even when the bad alternator was in it. The only time it was running bad was when my uncle came over and put the new alternator in it the first time (I was at work). Later I put the battery on the charger overnight and drove the truck and it ran fine. And the alternator would work for a while, then quit working.
The battery is from Costco and I believe it's a 9 year battery.