My 1999 expy 4.6L runs like what seems to be on half power. checked the coil packs and found that I have to power center pin drivers side coil plug. passenger side is tested fine with power on center and flashing on 2 end pins when trying to start. I am now being directed to the crankshaft sensor but would that effect power to the coil packs? already checked all fuses and relays not sure where to go next.