Flicker Or Intermittent Check Engine

New thread, I tried tagging this onto an old thread, but didn't get far.

1990, LX, 5.0, manual.

My check engine light will come one, then go off, and back and forth for about the first 10 miles when I'm driving. I noticed this new problem after changing plugs and wires. While changing those i found a broken vacuum line on the passenger side. The little grey one which comes out of the center of the vac block just behind all the air intake piping. I patched that vac line up with an over patch and sensor safe silicon.

No issues with how the car runs, pulls well, sounds fine, idles nice. But when I push on the engine, under load only, clutch in no lights, I get the check engine light come on, then off and on again when i gas it.

I think electrical issues, some kind of short in the dash panel. But I did pull codes today.

KOEO 85 13 1
KOER 4 11

Very rarely the yellow/red portion of the tach dash light will flicker also, not at the same time or interval as the CEL.

Thanks for the help guys.

OK, still happening. Not sure what else to do. Any help is appreciated.

I went over all the vac lines again and they are fine. I do not have a vac tester, but I'm looking into getting one.
Again no real trouble codes (aside from that 85) when I do the tests. But when I drive the CEL comes on for 3 seconds then winks off or goes off for about 1 second, then lights up again for 3 seconds.

Grasping for ideas I'm about to change the O2 sensors. Maybe they are in bad enough shape to work incorrectly, but not give a fault code? I don't know.

Took the dash apart and the bulbs and connections are good, no more flicker on the dash lumination bulbs (bonus made my bouncy speedo quite a bit better).

Well, throwing on new O2 sensors changed the RPM range of the flicker.
It still comes on and off.

Anyone have a write up on the procedure to smoke test the engine for leaks?

I won't say I've eliminated the possibility, but I did have the dash out and looked the electrical grid over, nothing obvious there. Connections were good, the lights all work well.

CEL seems to be a symptom of engine or vac. It clears up once the car/cats get nice and hot after about 10 miles. The exhaust smells rich. Seat of the pants feels a little low on power, just not as crisp as it should be.

I know that 4 and 1 are not codes, those are flashes from the CEL light when I do the tests after jumping the test port. Jrichker posts a method on this fairly regularly, I just report those flashes to imply that I do see the test beginning and ending. I wish I had an actual code reader since I am struggling big time with this issue. The "flashing" CEL I get does not manifest on test or if I idle the car, only under load and around 1500-2000 rpm.

But hey, you're the first to respond since early December, so maybe everyone is as stumped as I am.

Finally did the smoke leak test.
Only 2 places the smoke came out I don't think are an issue. One is from under the throttle, looks like along the bolt with the spring there. the other is that piece in the first picture.