mechanic question for 1999 ford expedition

Got question for the mechanics out there. Got a 99 ford expedition 4x4 5.4 liter.
vehicle was running bad so we replaced some vacuum lines, pcv valve and change plugs. first after replacing vacuum lines it ran great for 2 weeks then started running rough again. We change the other items I mentioned it still is running bad. a mechanic I know troubleshooted it down to the pcm. when I change the pcm(after matching XL1F-12A650-FE number up) it won't start. Disconnected battery for 10 mins then tried again still won't start. But it will if the original pcm is in but runs rough. Anyone got any ideas I'm stumped.

First of all there's a few things that can be going on firstly you could have been given the wrong PCM by mistake.

Secondly you could have gotten a faulty PCM.

To my knowledge there is no manual programing required for those so its pretty much plug and play..

With the old PCM how long are you driving it after taking it out..

They have a15 minute KAM or Keep alive memory in them..IF that is let to run out then it may still be running rough..

Also it takes 15 - 20 miles of driving with the reset PCM to allow it to relearn how to deliver the fuel.

I tried to computers matched up the numbers that read needed to match and the ones the my mechanic buddy told me to match. Still nothing. tried disconnecting battery for ten mins still nothing.

when we troubleshooted it . We came up with no signal from the number 7 driver. changed the number 7 coil and still running rough. that is when we read out pcm and the # 7 driver had no signal.


didn't try to drive for 15-20 miles to reset.

what I just noticed is the anti-theft light flashing when I try to start.
Not sure how to reset.

Your PCM may have to be programed to your Key PROM

I'm sure that involves a service center huh?:(