GM Forum - Buick, Cadillac, Olds, GMC & Pontiac chat - 1999 Bonneville mystery problem-HELP!

I have a 1999 Bonneville SLE with the 3800 engine. I have been intermittently having this issue, and I can't seem to figure out what the issue is so it can be fixed. The car dies while running, almost always when I hit the accelerator after coming to a stop. The car will also die when I stop it at a stop light or stop sign, although that's not quite as frequent. The check gauges light sometimes comes on when this happens, sometimes not. When the car dies in this situation, the engine will stop running and my power steering will quit working, but my radio and air conditioner and whatever else will stay on, so the car doesn't turn off completely. However, since this first happened about 3000 miles ago, the check engine light has come on and stay on. I have taken it to an auto parts store and ran the computer on it, and what has come up as the result is that the catalytic converter is running below efficiency. I do not have the code for this. However, I have talked to two different mechanics and they both say that the catalytic converter would not cause this problem. I have taken this car into three different mechanics and they all say that they can't find anything wrong with the car. I had the crank sensor changed just in case, because that seemed like the logical thing wrong with it. That has not fixed the problem. Someone on this forum suggested that the gas gauge could be reading wrong, as when the problem first started the car was only doing this at 1/4 tank of gas or less. Now the car is doing this with 3/4 tank of gas, so that's not the issue either. My car has also recently started dying while I'm driving down the road, at any speed, really. When this happens, the RPM's drop to zero, and when I push the accelerator, the car will do nothing...but it will still be idling. Every time my car dies, it will start back up immediately, or almost immediately.

Today, I had the FPR checked, as I was told on this forum that it causes this problem. The mechanic said my FPR is absolutely fine- and brand new, in fact. So that's not it. I asked my mechanic about the Cam Sensor and he said that this problem would not be caused by a faulty Cam Sensor. I have been in contact with someone on this forum and he mentioned that it could be in the ignition harness area- where the wires move and touch the harmonic balancer and rub through the wire until it shorts out, and that this would cause the engine to die. I haven't asked my mechanic about this yet, but we're both at a complete loss at this point.

Does ANYONE have any sort of idea of what would be causing this problem? I just want to fix this and move on, but it's proving difficult. Please help.