Around 1 year ago I had the cambelt changed on my 2012 Galaxy 1.6 Ecoboost. After fitting the new belt the garage could not start the car. After several months of trying different remedies the garage took it to a Ford main dealer who diagnosed a faulty ECU and changed it. My local garage paid for this and I paid only for the cambelt change (the car was running perfectly when I took it in). When I got the car back there was on occasional stutter and hesitation as well as a general lack of power and after several months of use the average mpg has settled at 32 compared to 35.5 before the cambelt change. When I got the car back it had been off the road for 5 months and I initially thought it might improve with time;  I also changed the spark plugs and coil packs. After several months of driving it is clearly not going to improve. My question is, could the cambelt timing be off by one tooth? I can see that this could worsen the performance on an engine without variable valve timing but wondered if the VVT on this engine would just correct this. Or is it more likely to be the ECU mapping? I bought an OBD2 tool and no codes are showing and the engine fault light has never come on.

It would seem to me that the most likely problem is the timing is out.

Or the replacement PCM is not configured correctly