99 camry 4cyl 240,000+ miles. misfire stops after completetly warm.

Which ever wire is sparking, replace the coil head that sits right above the wire. Sounds like the coil is probably jumping spark which makes it appear to be coming from the wire.

Dont know the number of cyl but looking at engine far left cyl . How can the spark travel thru a 8mm brand new plug wire and wrapped the entire plug wire w two thick layers 3m electrical tape. The fire jumps out of the wire 18" away from coil pack. I can grab wire w my bare hand and touch coils all over and not get zapped. Ive been hit by many coils and this is not the same. I feel nothing and we're talking about several thousand volts. W out a doubt it should go thru me.

Ill switch the the two coil packs and see if it jumps from the other wires. But as of now its only jumping from one plug wire. I can raise the wire an inch or two above the valve cover and the it stops the fire from jumping and the electrical popping noise too. Very strange ive replaced a lot of coils. Work on cars trucks bikes daily, never seen this. Coils are funny but the only thing i can think of is a hole in the coil and spark travel thru valve cover and jumps back into plug wire. Also it goes away after its warmed up. If the coil is bad or a hole or over shooting voltage why does it stop after its warm?

Ok....you never said what end of the wire was sparking in your original post. Have you checked the plug itself to see if it has cracked the glass? I have heard of carbon transfer...where the spark will actually travel through the carbon build up....

The wires are brand new along w plug wires. Correct oem plugs and 8mm wires. The fire jymps out of the wire to the valve cover about 5/8 of the length of the wire. Fire jumps out a little closer to the plug but almost in the mid way of wire. Just past the pcv inlet to valve cover

Mist the wire with water and hold it away from the valve cover. See if voltage is going through the wire. If you are not getting zapped, that would mean that stray voltage is somehow traveling through the engine from some other source. Check grounds, and check any wires that appear to be touching the engine. I once had a similar issue. My forearm was wet with sweat, and as I grazed it along the inner fender, I could feel a low dose of voltage going through my skin. It was actually a bad coil wire on my ' 89 Toyota 4X4. I had replaced all spark plugs and new wires. The only wire I hadn't changed out was the coil wire. That was the culprit the whole time.