travr6

I have a 2012 3.5L twin turbo ecoboost.

I had the timing chain rattle and an issue with the coils. I was getting 17 mpg before the fix.

I had the timing chain repaired and now it does not rattle when I start it.
While in for service it was determined that the computer was not telling two of the coils to fire.
A new (used) ECU was installed.
Also installed new plugs and replaced all of the fluids.

Truck runs well now but shudders a bit at speed and surges slightly at idle. It did this before the repairs and seems to be exactly the same.

The other main issue is that my MPG dropped to 10 mpg after the repairs.



My questions are:

1. Does the ECU need to relearn or should I have it reprogrammed to deal with the drop in MPG? Is there something else I should look at?


2. What would the surge and shuddering be?



I am not getting any codes on the truck. I drive like an old lady but I have been stomping on it quite a bit lately trying to see if I can get a code to pop up.
The mpg drop is not from this. I checked it during a 300mile highway trip.



Any suggestions on any of this?