94 ford ex 6 cylinder 4.0
I have changed plugs.
replaced O2 sensor.
replaced radiator and thermostat 185 deg
cleaned M sensor, one with wires.
Any suggestions why I am getting such poor gas mileage.
My check engine light goes on and off all the time

 

Check it for codes and see what it says/

 

I have seen a common problem among explorers (mine right now) have a tendency to have a problem with the fuel pressure regulator attached to the fuel rail. they can get stuck in the open position which will drop fuel pressure from normal 35psi to as low as 15 or 20psi which will cause your gas mileage to make you feel like you are driving a chevy LOL this part can be replaced by visiting a local autozone or advance auto parts. make sure you buy he GP Sorenson aftermarket part as i have found the others do not fit well with your current vaccum lines.

 

I don't know if you've solved your problem yet, but here's some tips.
-OE temp for thermostat is 195 deg. the computer wont run right until it warms up properly.(this alone bumped my mpg by almost 2)
-Pulling the codes is definitly a good idea.
-You can test the TPS and ACT sensors with a voltmeter, to make sure they're working properly.
-FPR could be the culprit
-the usuals: filters, plug wires, tire pressure, etc.

Good luck

 

You may have fixed it by now, but on my '93 the drop in milage when everything else checked out OK, was due to the mass airflow sensor.

 

I have to agree. My 91 did the same thing while I was in Germany and it turned out to be the regulator. Sorry thing was I had to take it to a Chevy dealership to get it fixed.

My explorer had poor gas mileage, ran very rough and the mix going into the egine was fuel rich, to the point were you could smell the gas coming from the engine. No problems since it got fixed. Definetely worth checking out.

Marco