G'day fellow Ford devotees, I own a 95 NF fairlane with the 5L Windsor, it has suddenly developed an odd misfire once warmed up (about 20-30 k's of driving/10-15 minutes) now straight up I know it has dud oxygen sensors because it had a weird backfire through the airbox about 1 minute after start up that lasted till it got to operating temp - I eliminated this through trial and error with fuel pumps/maf sensors and leads/plugs - finally removing the HEGO fuse from the panel next to the coolant tank, it solved that cold start issue, even though it run rich and cost more to run, this new miss though is as stated once warmed up and driving, it's like miss that drops the engines revs but it doesn't seem to effect the voltage gauge/as in like an electrical hard fault where the mains power is getting cut/dropping, iv'e changed dizzy cap,leads,plugs and the ecu/power relay under the coolant tank, still no good, iv'e disconnected the battery to clear faults but still no good, gonna end up taking it to an mechanic/electrition but thought I'd throw it out hear to see if anyone has an idea I could chase up, I know the most common answer will be have you put it on a scanner and tested for fault codes - I wish, but I don't know anyone with one and have access to one.
CHEERS in advance

Put the hero fuse back in. All you did was slow down the O2 sensor heating. They heat up anyway on their own but take MUCH longer

So you either have a dud O2 sensor, or an earth problem, or you screwed around with the O2 wiring

I swapped my O2 sensors wiring once. So one bank went way lean and the other went way rich. Ran like s**t until the Ecuador eventually failed one out then ran normally on one sensor

My el now (just converted to au v8 with coil packs) has a half dud sensor. It works 50% of the time. When it doesn't, the car shudders lean for a few mins on one bank then the sensor gets bypassed. When it works, engine runs perfectly

Start with the earthing test. Make sure that the earth at the back passenger side of the manifold is ok. Then the earth straps

After that - sensors. Instead of pulling the fuses completely unplug each one. That stops them from giving a signal even if they do heat up

Then - perhaps go see a. Auto leccy

Also - don't use pec branded sensors or any eBay ones that aren't Bosch or ntk. They do t work as well or don't last

Nigel