91 2.3 idle problem manual trans

Just adding this info in because it may help solve my problem. A month or so ago I posted how my check engine light comes on and my rpm gauge jumps all over the plays. Even though the gauge jumps, it does not effect the true idle of the car. Now my car starts up fine goes to idle around 800 to 1000 then drops to 500 or lower. At that point it ether stays idling around 500 or just dies. Car will start right back up after it dies. If i feather the pedal and keep the rpms around 800 for 5 minutes and let go off the gas the car will idle fine or if I drive it for a few minutes it does the same thing. The only changes i have done to this car lately is that the day before the idle problem start witch was this last Friday. Is that I disconnected my negative cable to hook up a new socket for the light under the hood. I also put on a new clutch cable. I did a full tune up about a year ago and I have only put 5000 miles on it scenes then. I am bout to just take it down to the Ford dealer and have them run an engine diagnostic if i can't get this fixed over Thanksgiving week end.

Thank you for any help