the coil
You need to adjust your idle.
because of ignition coil faulty.due to mountings,abnormal fuel pressure.
If it helps the fuel pressure at the fuel rail should be 3.3-3.7 bar with the engine idling. The holding pressure after 20-30 minutes should be, system pressure - 0.5 bar.
Taking your foot off the accelerator.
BAd radiator cap, low coolant or (leaking), Bad thermostat, cooling fans not turning on.
The transmission fluid on a Chevy Blazer can be checked by idling the engine and allowing it to reach operating temperature. The dip stick can then be removed and checked based on the markings provided.
There is not much information here because different automobiles can the same symptom with a totally different cause. Giving it my best guest I would say that you have a leaking fuel pressure regulator the engine can handle the extra fuel when driving but run much too rich when idling.
The oil pressure is low or the sensor has failed.
It is idling. This is hard for an engine to do smoothly.
Probably wheel bearings or wheels are unbalanced
A low oil pressure reading when idling for a 1986 Fiero is normal. As long as the oil pressure goes back to normal when the car is being driven, there should be no problem. If it is not, then the oil pressure sensor or the oil sending unit should be looked at.
There are several things that can cause your Jeep to stall while idling. The timing may be off or your fuel filter may be clogged.