Engine 1988 LX 5.0 shaking violently and popping under acceleration - video inside

lepryy said:

Hey everyone, I've been having some very concerning issues with my 1988 5.0.

For starters, the car has completely stock engine internals. Here's a short 30 second clip of the issue I'm having: View: https://www.youtube.com/watch?v=INJaNCEc_aE


The issue is almost always in a high gear running at low RPM. In the video you can see I'm in 5th going roughly 40-45 mph. The car will cruise relatively okay, but once slight throttle is applied, the entire car shakes like it's going to fall apart, has basically no power whatsoever, and occasionally backfires (95% sure it's backfiring through the intake not the exhaust).

This issue began about 2 months ago and completely at random. It got better for a couple weeks but recently it's become so bad I'm worried to drive the car for fear of damaging it.

Here's what I've already done:

1. Adjusted timing to about right on 12 degrees. I tried to do the factory 10 but she seemed to run much smoother at 12. Previous owner had it at 16 for some reason?
2. Local mechanic who owns at least 6 foxes suggested to delete the EGR. So I got the b-off kit from LMR.
3. Visually inspected every spark plug. I did not notice any fouling. Gaps were consistent.
4. Checked all plug wires. Cylinder #6's wire was reading about 16k ohms. The rest hover anywhere from 9-12k ohms. I replaced the one reading high with another I had of the same length that was reading 8k ohms. There is so much conflicting information out there about checking plug wires I have no idea what I'm doing. If money wasn't extremely tight I'd just order a new set of wires off LMR. But I can't afford to do that and not have it fix the problem.
5. Adjusted the idle screw. TPS was crazy low (like 0.5 volts), I set it to 0.95. Performed a base idle reset. Didn't do the whole disconnect the battery for 30 minutes part though.
6. Found the vacuum line that runs from the underside of the upper intake to the charcoal canister was super rotted. Replaced it with some fuel line I had laying around (only temporary but it works for now).
7. Pulled codes. During KOER test I received codes 44, 94, and 33. I think 44 and 94 may be from my X-pipe that does not have the smog port. The smog pump is still on the car and has a belt on it but no tube to the exhaust. It's been like this for at least 3 years. Also I believe code 33 is EGR related (like I said I removed it) but also my kit came with the little plug that is supposed to tell the computer the EGR is functional. Idk.

That's where I'm at currently. If anything the problem has only gotten worse. I'm literally at a dead end here folks. My car is running like absolute ass and I've already entered it in the Foxtoberfest show. Any help and suggestions would be greatly, greatly appreciated!

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