I have a 95 Bonneville, with a 3.8L Series II Non Sc. The problem is that sometimes while im driving, doesnt matter the speed, its when i come to a stop that causes the trouble. long story short, when ever i come to a complete stop, only when the car is in the gear, it stumbles as if it wants to die out but it doesnt, the oil pressure gauge flucuates back and forth as well as the voltage gauge. if u can see in the picture below on the oil gauge, the black arrow shows where the hand sits at while driving and at idle. The red arrow shows where it jumps back and forth to when the stumbling starts. And to add to that you hear a pinging sound coming through the exhaust pipe. Before you start to reply, let me mention that the Bonne runs fine on take off, acceleration, and at idle WITH THE CAR IN PARK, no misfires, no leaks, not burning oil at all. Its jus the stumbling after coming to a stop. Another way to describe it is, it feels like the car wants to slightly take off, jerking a little like, "Doum.......doum..doum......doum......doum" and every time it does that you get the pinging through the tail pipe. NOT BACK FIRING ! Changed plugs and wires and coils. Had codes pulled, only code it show is the knock sensor, nothing major. any suggestions ? hope the picture can be seen !!

i'm no expert when it comes to engines, but um knock sensor throwing a code, nothing major? correct me if i'm wrong but that seems like somehting to take care of like ASAP

The gauges jump around because of the low RPM. First thing I would do is look for a vac leak. Spray carb cleaner around all the vac lines including the EGR tube and listen for changes in the RPM

It has two knock sensors one set up to obd-I and the other obd-II, car running as obd-II thats y the knock code pop in.

Oil pressure guage may be due to a fualty oil sending unit... or just the voltmeter because of the irratic idling.

I would check out those vacuum lines though. Listen for a hissing coming from under the hood when you're spraying the hoses, that can help identify where it'* coming from too.

Possibly a bad IAC valve (idle air control valve) though too...

Thanks for the help found the problem, one of my coils is not tighting down to the module cause one of the screws is stripped out in the threads !! This was a needle in the hay sack !

How did you find the problem? Did you pull the plugs and inspect them, or did you just get lucky?

yeah i actually started with the plugs, and they werent that bad but the car was still doin what it was doin, so i figured id clean the connections between the coils and the module. but as i went to take off the middle coil i noticed that it was takin me a long time to unthread the bolt, kept spinnin and spinnin. started the car and push down on the coil and u could tell the differencde pretty quik in the idle. havent felt this much power in a few months. i can burn rubber now again !!

Didn't see this one coming.