AMC 401 bizarre problems (EBL system)

[FrankNB]

Hi, I'm throwing this out here cause I'm a bit mystified with a problem I've been experiencing with the 401.

Back in late October I replaced spark plugs (regular copper plugs) gapped to 0.060", cap and rotor (msd billet distrib), MSD TFI coil. I was having a lot of backfiring during decompression stopping (manual tranny) before the plug change and the plugs fixed that initially. Then, my fuel mappings seemed all off (Dynamic EFI EBL with 454 Holley TBI, 80lb at 26psi), that I had to enrich and recenter the table by almost 10%. Eventually I got it all tuned up again . A month later, I drive 80km on the highway all was working well. I park it overnight then suddenly the next morning the damn thing runs way lean again. This time I had to re-center the fuel map table by another 20% and it's been running like crap ever since.

So two days ago I checked all the vacuum lines, replaced the broken ones and same with vacuum port plugs. I then added some fuel injector cleaner in the gas tank, some Seafoam (yea I'm that desperate) through the brake booster vac hose and half a can in the gas tank too. Not much change yet.

I've checked the fuel pressure and it's at a steady 28 psi and tomorrow I'm going to pick up a cylinder compression tester to make sure there's nothing catastrophic there.

The temperatures have been dropping steadily outside, but I mean I've ran the jeep for two years with the same fuel mapping until last October. I just don't know anymore, I might put back the old TFI coil and see how things go from there.

Any suggestions; cleaning the IAC, the injectors, map sensor or something?

Thanks for any input.