It seems that the car begins to run rough like its missing. The battery light is hit and miss( comes on and off).Recently now its seems to be staying on. I had two coil packs replaced last year due to a chk eng light issue which turned out to be an intake leak. Repaired at the dealership, no more issues until just recently. I am wondering it the other coil packs are in need of replacement or if there is another issue going on. Perhaps the battery itself needs to be replaced ( or as well as the coil packs)?
OK I was thinking that could be part of the problem. I just didnt and perhaps dont understand why that would make it run rough ( skip/missing as though it was a coil pack issue) I will let you know how the load test on battery works out.
While you are at it get the alternator checked. Is the check engine light on also? May have two or more problems. Low voltage can cause run rough but should cause a no crank condition, at times, as well.