2004 Monte Carlo 3.8 Non-Turbo......for months Ive been trying to find the problem with no idle, rattling, loss of power, just running like hell. So, this one I need an expert to tell me how this fixed it. I pulled all the wire caps off the three coils. I had my dad crank it and only the top coil and bottom coil was tossing fire across the post, middle coil was dead. I then move to check it, the dead coil to the top position, dead. So I found it, dead coil in center of the trio. well, just for the hell of it I left the dead coil on top of the pack and put the good one where the dead one was and I bolted them all back down, put caps on them and bamb!!! Run like a new car. Well, almost. It purrs like a kitten in idle and at lights, but I still have some hesitation on the highway. I mean it will work its way to 80mph but I have to baby it. Slow speed travel and hills and corners, it will set me back in the seat, so Im thinking fuel pump maybe. But every problem I have been beating my head on the wall for is gone. Heres another thing, my guage inside shows charging great, but my battery is dead when it set overnight. SO, as someone that is an expert on prior 75's what am I REALLY missing here? A dead coil just dont start working becuase I moved it to the top position. Any help would be swell. Thanks guys.

 

Is it possible there was corrosion on the coil terminals that wiped off when moving it?

Have you had your battery load tested?

TBH its awful hard to diagnose drivability issues online with near zero data beyond just the symptom. Do you have a scan tool that can read sensor data? You'd just need to look at the O2s and fuel trims to confirm or disprove your theory on the fuel pump dying.

 

I agree with bumpin.
But if you are just fishing around trying to find the problem.
There is also a fuel pressure regulator/valve on these cars that will go bad, some will even blow the intakes off too.
Fuel Filter was changed last?
Now the other crazy thing that will rob power is a bad Catalytic Converter.