2006 Hyundai Sonata Large vibration on entire front of Car!

Engine Mechanical problem
2006 Hyundai Sonata 110000 miles

I took my car to a Sunoco gas station for a tune up and have the main drive belt replaced serpentine belt. Three days later I was just starting driving and the engine was not too hot because I has driven only a mile and when I got between 45 to 55 MPH there was so much vibration coming from the engine area I thought the engine would drop out in the road. I took the car back to the gas station and they re checked the engine mounts and engine mount bolts. The vibration only happens during the first 20 minutes of driving for he most part. I am now thinking that when the mechanic replaced the spark plugs that he damaged one of the cables going to spark plugs however I wanted to get your opinion.