Toyota Repair: Camry LE 2004 motor mount bolts

Question
All four motor mount bolts just changed on my 2004 Camry 4 cylinder automatics with 246000 miles.When I picked up the car there was a loud roar when it started, and similar noise when It idled. Sounds like muffler noise but the noise disappears when the motor is revved and the noise can only be heard when inside the car. I thought it was a new vibration causing some parts to rub together but put up on the lift nothing can be found. Could the mounting bolts be improperly torqued causing a new vibration? The mechanics also installed new plugs and cleaned the fuel system.Could this have caused this problem? The car did not have this loud noise before the work was done on it. Thanks in advance for your help.

Answer
hello, I agree with you that this new noise is a result of the work that was done, it's hard for me to say what may be causing the noise except that there is most likely some contact between the engine or exhaust system and the body of the car, they need to check for this, replacing the plugs and fuel filter should not cause this type of noise.