93 K1500 5.7 engine surge at idle

Hi,
I have a 93 K1500 5.7 that has developed a bad engine surge at idle. I have noticed a slight miss (interminent) at idle and seemed to be getting worse, now it surges real bad, lopes and almost dies at idle. The surge changes from bad to a little better but never gets good. The tailpipe is real sooty like its running rich. The SES light is not coming on. Seems to run good at highway speed? Have noticed temp gauge does'nt seem to be showing as warm as normal?
Any suggestions would be greatly appreciated.

Hi,
I have a 93 K1500 5.7 that has developed a bad engine surge at idle. I have noticed a slight miss (interminent) at idle and seemed to be getting worse, now it surges real bad, lopes and almost dies at idle. The surge changes from bad to a little better but never gets good. The tailpipe is real sooty like its running rich. The SES light is not coming on. Seems to run good at highway speed? Have noticed temp gauge does'nt seem to be showing as warm as normal?
Any suggestions would be greatly appreciated.

Things that can make it run rich:
- leaking injectors. Spray should be coned shape
- fuel pressure too high. Should be 9-13 PSI at idle
- leaking fuel pressure regulator. Internal to TBI so hard to test.
- Bad 02 sensor
- Bad ignition. Worn dist shaft bushing, bad pickup coil, ignition module, coil, wires, plugs, dist cap or rotor.
- Bad MAP or vacuum leak to it or pluged vacuum port. Note here that high vacuum (idle) is less fuel so if the MAP does not hold a vacuum it will run rich.
- Mechanical issue. Burned valve, value guide, rings, etc.

Check fuel pressure and check MAP vacuum hose, TBI port for the MAP and make sure it holds vacuum. Look at the injectors for dripping.

//2000CAYukon

I have ended up changing the intake gasket due to coolant leak and this has seemed to fix my idle problem also, must have had vacum leak in intake. Haven't driven it much since change so may have to repost on fix.