idle rpm fluctuation

I have a 4-door 1999 V6 3.4L. When I start the car sometimes, the idle rpm fluctuates from ~500 to ~1500 and the engine sounds like it's about to die, but after a minute or two it idles normally at 750 rpm. This problem started about a week and a half ago, and it did this about 3 or 4 times. The rest of the time it starts normally. Today the car did it again, but this time the service engine soon light was flashing at the same time then turned on steady and won't go away. Any ideas on what is wrong with it?

Welcome to AF.

Since you have a SES light get it scanned for any odb-ii DTC error codes.

When SES blinks it means a misfire situation was detected. It could be as simple as spark plugs and/or ignition wires.