The front and rear engine mounts are made out of steel and rubber and they are filled with hydraulic fluid. They are also vacuum actuated using engine vacuum and that is computer controlled. When they go bad, they can leak hydraulic oil and/or they can leak vacuum (air) which will affect the engine idle.
Front Engine Mount from Acura/Honda dealer is part # 50800-S0K-A82
Rear Engine Mount from Acura/Honda dealer is part # 50810-S0K-A81
Rear Engine Mount from AutoZone Duralast is part # 9149
Valve Assy, Electronic Control Mounting Solenoid for 99-06 TL is part # 50913-S87-A81
Note: The side engine mount is not hydraulic or vacuum controlled.
High mileage Acura = over 600,000 miles.