I have a '93 5.0 that runs great at start-up, idles fine and takes the gas well. The problem though is that just above idle, such as when driving in a parking lot or taking off at a light in heavy traffic, it is very rough (almost like its missing) and has poor power and response. (and it seems to get worse as the truck warms up) At first, i thought it was bad gas and put a treatment in the tank and changed the filter after running that tank out. This did not work, so i checked the vac lines and electrical connections, changed the plugs, rotor and cap. (the plug wires are relatively new and of good quality) My EGR also looked rotten and i replaced it. These did not work either, so i ran KOEO and got a system clear. Next i checked base timing and it looked right on. Then i ran a KOER and also got an all clear. I know that the IAC valve and the TPS can cause similar symptoms so figured i would check the IAC first because this is a high mileage truck and have heard that these will get dirty and cause problems like the ones i am having. I was going to clean and test it and if it was in range, put it back on and go from there. (replace it, if not) My current problem is that my Chilton's & Hayne's manuals are not clear as to the probe placement to check the OHM,s range and i did not know if the diode would be damaged if i trial-and-errored my way through. Does anyone know the proper placement of the probes for testing the IAC, and/or have any thoughts on my driveability issues?

 

good luck man. mine is doing the same thing and it's a challange. look on youtube they have some good tutorials on testing sensors with meters.

 

http://www.fordfuelinjection.com/?p=39 & https://www.f150forum.com/f33/how-se...-1991-a-31505/ Unless your planning on changing your oil soon, go 1/3 through the brake booster Vac line & 2/3 in the gas.

 

thanks for the link! wasn't sure if i could take the iac apart. gonna throw it on, unplug it & see if its good or not.

 

good resource from ymeski56. will let you know anything i find that works/doesn't work.