Rough idle 06 Saturn Vue 3.5 V6

I have an 06 saturn vue with a 3.5 v6 honda motor and drivetrain truck has just about 75k on it I recently had the timing belt done it was a full kit (gates brand) with the idler, pulley, tensioner etc. Also changed the water pump(this was done by a certified mechanic) my problem is now the truck is idling rough! It runs fine on the highway plenty of power and great gas mileage but you can feel it in the steering when you are at a standstill idling very eratic even when the truck is cold still rough idle I bought it back to the mechanic he says its the way they idle I said no way truck idled smoothly before timing belt replacement put truck on machine no codes nothing! (I wanna choke this mechanic!) And I have used him for years with no problems! Its evident theres another problem! I also noticed lifters are noisy (and I noticed motor is shaking slightly) cause its not idling smooth I was told lifters need to be adjusted on the 3.5 honda motor and that there is a knock sensor that could be retarding the timing and making motor idle rough! Is thistrue? Should I replace the egr and pcv valve and see if that helps? I am going crazy with this truck I have did a load of other work to it also including new tranny so I need to make it right! So any help would be appreciated! Remember this is a honda 3.5 v6 motor in an 06 saturn vue!Thank you! Please help if you can!