CEL codes p020x and p030x

Hoping someone can help point me in the right direction with solving my rough running rig...

Bought my XJ 4.0 new in '96 and have 225000 miles on it. Three years ago I started getting p020x and p030x codes along with an occasionally flashing CEL and running real rough. The CEL had been coming on every few months, and running some injector cleaner through the tank always resolved the problem.

Then about three years ago I replaced the distributor, rotor, plugs and wires, coil, PVC valve, fuel injectors and ultimately the PCM until I finally got the CEL codes to stop. Since then I would occasionally get a CEL, usually after towing something heavy and it would clear itself in a day or two.

A few days ago, after hauling my fifth load of a 1/2 cord of firewood the CEL came on again and noticed rough idle conditions. On/off x3 on the key gave me several 27 and 43 codes, so I used CLC electrical cleaner on the injector connections. Afterward the jeep started running real rough, especially at about 45 mph. Had NAPA Auto scan the codes and got p0201, p0202, p0205, p0301, p0302, p0305 andp0306.

Anyone have any suggestions on where to start looking for the source of these errors?

The P020x codes are injector circuit malfunction, and the P030x are misfire which I'd suspect are caused by the injector not working. I'd start by looking at injector wiring and the +12 volts to the injectors. They all share the same +12-volts feed from the autoshutdown (ASD) relay, and the PCM controls the injectors by providing the ground to open them. The ASD relay has been known to go bad or have bad contacts. I'm just not sure how the problem would be heat related.