I have a 95 f150 4wd 5.0 5 speed map sensor truck I bought about 4 months ago. My first ford truck (not first truck though). It was getting about 10 mpg changed the o2 had lean code. It has a problem when coming to a stop with the engine holding the truck back(decell) when you push the clutch in the idle drops like it wants to stall.Mostly when cold. It would stall before changing the 02 but now just acts like it will. Now i get about 12 mpg not running it hard. Only code last time i checked was 33 egr. The egr works if add vacuum to it at idle it gets rough. The truck runs well has 109,000 on it but tail pipe is black. Doesn't seem to miss and idles good. Plug wires look new, plugs look ok, just changed the fuel filter it wasn't clogged, just changed oil with new air filter. It has 3.55 gears with 31 tires.If it wasn't for the wanting to stall and black tail pipe I would think it was just very bad on gas. Any Ideas?

 

Check the water temp sensor, that also controls the fuel mixture, my old truck had a loose wire to the sensor and was running rich.

 

did you disconnect the battery after the O2 sensor change?

 

did check the plug on the temp switch, also didn't disconnect battery after 02 change but did clear the codes.

 

Run the codes again and post them all up. Code 33 is usually accompanied with a code 41.

 

Then again, you're supposed to have 3 digit codes...

 

I pulled codes today and got 111 then 1 then 128 but I was messing with it earlier and pulled the vacuum line from the map to see if I had vacuum.

 

Check your fuel pressure at the rail. Sounds like it could be getting more gas than it knows what to do with! (F/P regulator)

 

I don't have a pressure gauge but I did check the fuel regulator and didn't have any fuel leaking into the vacuum hose. I have also cleaned the iac, throttle body, and checked the tps with a meter it was smooth though the range. also bumped the timing up a little.

 

Fuel & vac pressures would be nice to rule them out. Fuel pressure bleed off time would also tell you if the injectors are seating closed.