How do you solve an engine vibration problem?

Following repairs have already been performed and still have problem: computer reprogramed, after market engine and transmission mounts installed, fuel injector cleaning, air injection reactor pump, air injection relay, air induction valve control solenoid, new ac delco spark plugs. Vibration was worse after the new mounts were replace. Mechanic into me over $2000.00 and now suggesting a new throttle body and replacing engine mounts with GM mounts.