Had a bad experience with mechanic. Claimed the heads cracked resurfaced them. When he returned car a vibration under hood, we looked and when you put foot of gas left side of engine lifts up out of the car
motor mount on left side is broken or loose on 2002 Mercedes-Benz E430 4MATIC
If heads were 'cracked' not warped , then I wouldn't be worried about an engine mount. I'd sell the car before it blows up.
for sure the motor mounts are bad or not mounted correctly...was it that way BEFORE the repair?
I cant see how doing any head work would break a motor mount but if the technician did loosen the motor mounts to lift the engine in order to aid in the R&I of the heads they may have forgotten to tighten it after repairs were completed. I would bring it back and have them recheck their work and look to see if the mount is broken or loose, tighten or replace mount as needed.