Why would sparkplug caps unplug while running?

are plug wires--- disrt cap & rotor on correctly -fuel pump running ---jump timing -failing coil

Had same problem with my 98 c2500 350cu in. Found distributor cap shorted. Take number three sparkplug wire off of sparkplug, let hang and try starting. Mine started, which let to bad cap discovery.

sparkplugs,spark plug wire and cap and rotor,if anything the stumble is from sparkplug wires

Sometimes a plastic cover needs to be removed. Otherwise it's just unplugging the sparkplug caps and insert the sparkplug tool to loosen the sparkplug. Make sure nothing falls into the open sparkplug hole once it's out.

Check ignition lead - ignition cap and sparkplug. look signs of wear or cuts on the lead. The cap should be tight on the sparkplug. The sparkplug must be free of cracks and not unusually blacked out. Replace if in doubt.

Quick test is to open the hood in the dark. Let someone start the car and look for blue sparks around the lead and sparkplug cap. Be careful - keep away from moving parts.

Thats a misfire in cylinder # 3.Possible causes would be sparkplug,sparkplug wire,distributor cap,fuel injector or injector connection.

This is a misfire with you car. The problem will be in 2 places if the disributor cap is bad youll see what they call ,spark flash, In the rotor this cap has to be in a set position and it has a tendeny to ge displaced and that will have to be replaced., The sparkplugs as it connects to the cap may spark flash over and at idle you can see it. Now at the sparkplug wires they go it to the valve cover and the valve cover leaks oil into the sparkplug boot. This can cause a misfire.What you need to remedy the situation is a tune up with a new distributor and cap and rotor with new sparkplug,

Oxygen sensor only report the condition of the engine the rough running condition can range from a worn sparkplug wires to worn sparkplugs to valve problems to injector problems. with the cadillac deville a tune up should be the first attempt to smooth the rough idle with the inspection of the cap and rotor cap and rotor do have a tendancy to arc internally and create misfire so does sparkplug wire that can leak spark voltage to ground and create misfire. the spark plug wire especially if they are brittle and hard can create issues

the catalytic converter maybe pluged .

First you need to determin witch one is #1 on cap Witch usely is the one directly behind carb. or throutle body. than its perty strate forward from there rotor runs clockwise. Cap only goes on one way. Food for thought when you chg. cap or wires one at a time is the rule even for a seasoned mechanic.