Pontiac Repair: Gas gauge fluctuating and car stalling problems, fuel level sensor, monte carlo ss

Question
Hi
I have a 2002 Monte Carlo SS with a 3.8 and 58000 miles  I've been having problems with my gas gauge fluctuating, I have had the fuel pump replaced and filter. When the car is park and idling the gauge goes from full to empty. When I put it in gear moves to full and then bad to empty.
My stalling problem started 2 years ago. I was taking a trip south and while driving a night my car stalled without warning. It started right bad up. The garage told me the catalytic converter was clogged and had to be replaced. The problem got worse. The car would stall the security light would flash, head lights flashing, radio locked up could not use remote to lock or unlock doors, dome light would stay on and Car would not start. Took it to garage had to have BCM put on. That fixed all but the stalling, I've had it bad in the garage and they can not figure out what is wrong. No codes show up. I have heard that crank sensors can go bad and not put out a code.  Any suggestions would be very helpful.

Answer
Hi there Becky!

Your on the right path with a crank sensor. if the cars just shuts off and stalls like someone turned the key off then Yes a crank shaft sensor is a good "guess"/safe bet. I would look at that is the culprit. Do NOT USE ANY AFTERMARKET part for this only AC Delco.. a few othere possibilites would be a MAF sensor but usually they will throw a code p0102 when they act up and when they restart they run goofy and hesitate and buck and misfire. The other thing to look at would be a fuel pressure regulator the diaphram ruputes in them and they spill raw fuel into the vacuum line and that will cause a stall under the right conditions usually at an abrupt stop or when  you let your foot off the gast while at cruising speeds.. other then that not much else goes bad on that engine it is pretty much bullet proof.. good luck :)
As for the fuel gauge it needs a fuel level sensor on the fuel pump module assembly VERY VERY common on just about any GM car of that vintage.. I would suggest you change brands of fuel as well high sulfer content in the gas causes the sensor to go bad.