check engine Code – what does it mean?

96 5sp 3.8 117k
Autozone scan said: 1406 - auxiliary emission control.. dude looked it up – egr position sensor error. Neither really pins it down. Ck eng light will be on a few days, then off a few…no difference in performance.

ever since I had the car, I’ve had a subtle backfire when coasting ( in gear, foot off gas pedal, rpm 700+) …am told it’s carbon deposits in FI…poured in injector cleaner ($6 bottle), bought 3 tanks of hi-octane, no improvement -- don’t think that this (backfire) has anything to do with the ck eng light, tho, the light’s only been off and on for a few weeks….

seems like alot of this going on lol, what it most likely is is carbon deposits in the EGR track, take off your EGR valve, and see if it is being held open by a chunk of carbon, 90% of the time thats what it is, you can replace it, or just shake the carbon out of it, and then before you put it back on, fire up the car, it will sound like it has a really bad exhaust leak, cuz well, it will, rev it up a few times to blow the carbon chunks out of the track, and shut it down, then bolt the valve back on, and fire it up, and the light should be out.