Ford Repair: 1999 ford windstar xl 3.8 liter, 1999 ford windstar, ford windstar

Question
am working on a 1999 ford windstar xl 3.8 liter put it on a computer and it gave several codes lean on bank one cylinder 2 and egr valve and oxygen sensor so we replaced the plugs and cleaned the egr valve and it ran great but the next morning it ran good for about an hour and started to miss again so i replaced the egr valve and sensor for the egr valve and replaced the fuel filter whitch was clogged, put the computer back on it and the only code that it showes now is lean on banck one cylinder 2 also added injection cleaner and dry gas to tank but still has bad miss also notiiced that the air intake temperature sinsor  was giving a bad reading whitch was 196 degreas at cold start any ideas would greatly be appreciated .

    thanks Ronnie

Answer
These engines had several problems, most notably being the intake upper gasket and isolator bolts leaking causing lean codes. Also each cylinder has a port for the egr, these will plug up and can cause misfire or lean codes as well.

Another problem is head gasket leaking coolant, this can also cause a misfire.