I have a 2000 s2000 with a aem computer... about a week and a half ago I noticed it ran on 3 cylinders... coil is good... I have good ground, good power, and the aem says it's sending signal to that coil.... when it runs for about 20 minutes it starts to run on 4 cylinders and run fine... I think they're might be a short somewhere in the wiring... has anyone heard of anything like this before?

Thanks in advance,
Brian