After Changing The Missfiring Cylinders Wires The Car Was Doing Exactly What You Are Describing, Loosing Power And Such. All That Needed To Be Done Was To Reset The Crank Shaft Sensor Adaption. This Will Have To Be Done At A Dealer With Star Diag. Tester.all It Does Is Resets The 5 Operating Speed Ranges In The Ecm.this Is Not Common But In Certain Instances Will Need To Be Done When A Missfire Is Present.