Stalling I'm having a problem keeping this car running. sometimes it runs (idles) then dies when you try to drive it. Then it won't start again for hours or sometimes days. I have replaced the fuel pump and fuel filter. The carb has just been rebuilt, the part that you adjust the idle with has been rebuilt, gas cap was replaced, fuel line from pump to carb was replaced and moved further away from engine block to prevent vapor lock, and the distributor coil was replaced about 6 months ago. I am running out of ideas. Please help!!

Perhaps it needs a tune-up. The fuel injectors could be dirty; the idle speed could need adjusting; you might have spark plugs that need replacing or re-gapping. Best take it to a mechanic.

If it stalls when the brake lights come on then the idle is too slow. The high amps of the lights will load down the engine and lowers the idle.

Sometimes that's caused by a vacuum leak near the manifold area.

Sometimes air in the coolant will cause an idle problem. Air will keep the air temp sensor from sending proper info.
Hope this helps.
Sometimes that's caused by a vacuum leak near the manifold area.

Sometimes air in the coolant will cause an idle problem. Air will keep the air temp sensor from sending proper info.
Hope this helps.

Should be on or near the fuel injector supply rail.

change the fuel filter and check the fuel pressure

Engine stalls cold or RPM fluctuates at idle up and down or dies near idle.

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve but always run a OBD2 fault code as well as the cleaning procedure. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control. If the above cleaning doesn't cure your issues you need to have the computer controlled automatic idle speed control system diagnosed and repaired by a dealer or electronic engine control repair shop.

TRY CHANGING FUEL FILTER,COULD BE CLOGGED FUEL FILTER,FUEL PUMP FAILING,FUEL COULD BE CONTAMINATED WITH WATER.IF FUEL SYSTEM OKAY,CHECK FOR SPARK AT SPARK PLUGS,COULD BE FAULTY IGNITION MODULE OR FAULTY IDLE AIR CONTROL VALVE I WOULD HAVE VECHICLE CODE SCAN FIRST BEFORE SPENDING MONEY.

My Pontiac Grand Prix is also a 99, it has 216,+ thousand miles on it, it runs great, idles good, I need to replace the oxygen sensor tho as it shuts off on me while driving or sometimes coming to a stop. You might try checking the fuel filter and pump as well.

soundl like idle air control valve sensor
try a clean .............if no better replace

sounds like the idle control vale is sticking when it is cold. It is located on the throttlebody right at the air inlet

I just went through lots of troubleshooting and expense on my 1996. Whenever I would lift my foot off the accelerator and was below about 30 mph, the rpm's would starts jumping around and sometimes it would stall. If I gave it a little gas (accelerator), I could sometimes keep it running. It also backfired once in a while. Starts right back up. Also, if I let it idle while in part, it would die after 1-2 minutes.

I ended up finding a hole in the fuel regulator. About a ~$70 part if you get an AC Delco, but very simple to change.