I am looking for advice on how to proceed
 

The short version:
I purchased a 2008 P71 took the car into a ford dealership to have the dome light enabled and now the car is running like crap.

The long winded story:
I purchased a 2008 P71 from a seller on Ebay. I did my home work and rolled the dice, I can say it was quite a stressful experience, however I was very pleasantly surprised when the car arrived.

I had my mechanic give the car a complete extensive inspection and I even had him drive the car and he said it was very solid strong running car and gave it thumbs up.

I was going to have an alarm and keyless entry put in and talking to the installer he said it would be nice if the dome light worked.

After much research I found out it was controlled by the computer and it was referred to as "dark mode" and I needed to take it to a ford dealership it should only take less than a few mins for them to go into the computer and turn on the dome light.

I called my local dealer and setup an appointment. I dropped the car off and talked to the service guy and explained what I wanted done. I also inquired about the possibility of getting a cruse control put in down the road and inquired what that would intail. A tech there said that my car would need the cruse turned on in the computer and a steering wheel with the controls he said that it would cost about 350.00 total. I said that would need to wait for another time and he said when I decide just bring it back.

I went and had some lunch and came back about 40mins later and the car was done and waiting. I went to pay for it and the guy said that they had been able to get the dome light work, however that they also had to enable the chimes, and oh we also enabled the cruse control as well. I really thought oh well guess that's OK and I payed for work and drove off.

I only went a few blocks and realized the car was not running the same as it was before they worked on it. The car seemed under powered and the shift points seem off and almost as if it was slipping. I took the car back and explained the problem. They said that what they did should not effect how the car would run. I told them I would take the car for a few days and see if it corrected itself.

Thinking I was crazy I took the car back to my mechanic that had just drove the car and ask him to check it out again he drove the car and came back and ask what have they done to your car?

So back to the dealership, they went in and turned off the cruse control and ask me to drive the car for a few days and see if it was better. I have had the car for over a week and the car still is not running like it was before they worked on it.

Some things I have done on my end:

I contacted the guy I bought the car from and he said that its possible they may have corrupted the data somehow. He mentioned that they could get something called "as built data" and put it back to factory. He said I need to check if any special tuning was down to the car by the police department it was from.

I contacted the Anaheim Police fleet managers and he said that they do not do any special tuning above factory.

I got an "as build data number for the car from the guy I purchased the car from he has been very helpful.

The owner of the dealership called me and explained that he wanted his head tech to look at the car and he would need it for a few days so he could talk to ford. I am a bit aprehensive, however at this point I am desperate to get the car back running. I am taking the car in on the 29th.

Any advice on how I can get this car running correctly again would be greatly appreciated.

I know this isn't going to be easy, but The tech in the head or the head tech should be able to correct that while you wait in the customer waiting room. It could take some time, but not a few days. Personally , I'm getting bad vibes here ! I know also there are people on this forum that deal with this stuff on a daily basis and they will most likely be able to offer a better answer.