That you will.

By the way, I did put in new plugs and wires. Didn't drive it around enough to see a difference yet, but I think the problem is elsewhere. I did find one plug that had a stress fracture of sorts on each side of the ceramic.

Something interesting happened. I just went to lunch half an hour ago. Started the car, went to a place to eat, everything was fine. Finished eating, got back in the car, started it, SES code, but everything else felt fine. Got to work, shut the car off, restarted it, and SES Code was gone. I'll check for history codes when I get home.

Similar thing happened 2 days ago, but ignored it. I was leaving for the day, and the car threw an SES code the moment I turned it on. Tried to restart it 3 times, SES code stayed on. Drove for 2 miles, shut the car down and started it again, SES code was gone and stayed gone till today.

I may try swapping coils when I get home. I have one spare good one.

A bad coil would most likely give a misfire, and that would make the SES light flash. A leaking gas cap can cause a SES light like that. But only having the car scanned will say for sure.

The car does give a rough vibration under idle when stopped at a red light. If you put the car in park, pull the hand brake, and pop the hood, you can see the engine shaking a bit inside the engine bay. I don't know how the SES codes and sensitivity of those codes differ between OBD2 and OBD1.5. I'm just trying to narrow down that vibration. Its getting really annoying.

Is it possible for a coil to be failing but not yet failed?

A bad coil will give a sputter if you do a WOT run. Or just sputter all the time. Pulling the plugs and inspecting them. A bad coil will be darker because of the bad burn. If it'* shaking in the engine bay I would suspect a bad motor or trans mount.

Front engine mount was replaced 3 weeks ago. Rear one was replaced last summer and still looked good when I inspected it while changing the front one, but I'll check it again just in case. How would I know if it is bad aside from putting the car in drive/reverse, pulling the handbrake, and revving the engine lightly from inside the bay? Transmission mount is older, but it looks solid and doesn't seem to be allowing any vibration. Engine torque mount is still in great condition.

There should be 3 trans mounts, front left, rear left, and another on the diff cover, plus the engine mount. Check them all.

For an L27, are you sure about that?

I have 3 lower mounts as far as I could find. One for the rear left that'* solid, one for the front left that'* hydraulic, which bolts down right under the compressor, one transmission mount on the side cover that seems to be solid, and one engine torque mount on the top of the engine. What am I missing here? Rockauto only lists one type of transmission mount.

What engine is this for again, I can't keep up.