If I am not mistaken, the coil has a little plastic clip where it plugins, inspect the clip for a tight fit, if there is any damage replacing clip should solve the problem. I would also check the ground on pcm at the number 3 pin

It is true a poor electrical connection could cause heat to be generated and reduce spark quality - a close examination of the connecting pins should provide evidence of local heating if this is the case.
If the connections are good and there is no evidence of local heating it is possible the coil is consuming too much current or being left switched on too long by the ignition amplifier.

While it is possible to obtain some indication of this using a multimeter it really needs an oscilloscope and a skilled operator.