help please need your expertise

It's either a fuel related issue, or one/both of your coil packs is going bad.

From my experience, going from the 1930's vintage carbed cars I learned to drive on to these new electronic marvels, you have to get the codes out of them before you fool with anything. Make sure you got all the codes. The EEC4's will give them to you via the check engine light.

Then go into a book like Chiltons, or such, and see what items to look at.

Sounds painful, but nearly any other way you go about it will be a wild goose chase.

From the description you have, one bank lean, it could be some condition that is telling the puter to give it less than needed fuel. A guess would be that a dying coil pack would cause it to run rich, or try to run rich.

I think the MAP or Baro sensors are a good place to look, then on to the throttle position sensor. I have an 89 non mass air car, so its somewhat different.

You also need to figure out what bank one pertains to. Not sure on a dual plug 2.3 if it is separated by plug sets. I think, from memory, it means that one of the o2 sensors is giving lean indications. Since there is only one set of cylinders, and exhaust piping, start from there. I think it should tell you which o2 is lean.

Also search around here, there is nearly unlimited info on Ford engine controls.

However, I find it takes a couple hours of reading before I can go to testing....