I just changed a coil pack on my 1995 Isuzu trooper and it ran worse than it did with the old one. then it died and wouldn't start again, so I took the new coil pack off and it started and will run on four cylinders. When i try to put the coil pack back on it will not start. I am completely perplexed, any help would be appreciated.

So I just had a mechanic come over and we figured out that it was the plate that the coils sit on. 50 bucks at the junkyard and I'm rolling again.

 

FYI you can have both coil pack and mounting plate tested at your local auto parts store. It's usually a free test the only challenge is finding an employee that knows how to properly run the equipment. Be sure to have them test the mounting plate about twenty times so that it heats up enough to get an accurate test.