2.3L ('83-'97) Codes despite replacing o2 sensors and computer: P1132, P0141, P0135, P0136...

[nsmar4211]

1996 Ranger, 2.3L engine. Started throwing codes shortly after being purchased. Replaced both oxygen sensors, replaced the computer. Still throwing the same codes :
P1132 Lack of Ho2S11 Switches-Sensor indicates rich
P0141 02 Sensor Heater Circuit Bank 1 Sensor 2
P0135 02 Sensor Heater Sercuit Bank 1 Sensor 1
P0136 02 Sensor Circuit Bank 1 Sensor 2

Have also replaced all 8 plugs, wires, and coil packs due to running rough (and it turned out the primary plugs coil pack wasn't even plugged all the way in, so it was running on the secondary ones. And the wires were put on in the wrong places on the primary coil pack). Replaced the carbon canister and 2 sensors inline with that. Replaced the MAF.
Edit: Current symptoms are intermittant lack of power, once in a while random stall (it's a manual but that's not the stall).
Thoughts? Things to try next?

 

[RonD]

Fuse 20 in engine bay fuse box is blown, 15amp fuse

It powers the O2 heaters, if it blows again with key on then there is a short in one of the 12v O2 heater wires

 

[nsmar4211]

Thank you! Next culprit I was leaning towards was the wiring. Will check that fuse tomorrow!