Vibrate and Loss of power

[bobome]

I replaced the head on my 87 325is two months ago, recently it started to vibrate and losing power (most noticeable on 4th and 5th gears), then it would go away and the power back. Today, while waiting at a light, it started vibrating again and this time the 'engine' light came on. Anybody know what's the problem or where I should be looking? Recently, the brake light and plate light came 'on' for awhile in the interior, I thought those lights were out but the next time I turned on the ignition, those lights were not 'on'. It have not been 'on' since then. I don't know these are related but it just lots of little things happening that it should not. Please help. Your advice or suggestion is appreciated. Thank you.
Sincerely,
Bo

[Jeron]

What is the "plate" light?

I would start with plug wires, distributor and plugs.