Hi noes_oh,
Good to hear that you had success, AND thankyou for letting us know
I agree with Craig regarding the battery off for at least half an hour.
After that, if you feel the economy is not up to scratch, you will need some workshop equipment to analysis the motor's operation.
Just one question re the CVVT, when they replaced it did they clean the gauze filter on the oil feed line? Its often overlooked and must be clean. On the FD motors up 2013, it sits under what looks like a sump plug on the side of the head ( above the transmission / gear box). You should be able to see marks if it has recently been removed. (5 min job DIY)
Cheers G