Over the time the exhaust gas recirculation (EGR) system may become plugged with debris, the oxygen sensor may also be getting slow or 'lazy' around this time. When servicing or cleaning the EGR system, it is a good idea to replace the oxygen sensor because it works in tandem with the EGR system.
Resources for the Repair and Maintenance of your 1994 Toyota MR2
1994 Toyota MR2
1994 Toyota MR2 Problems
The engine mount on the driver side of the car can wear out on cars with high mileage. This will put extra stress on the other mounts and the faulty mount will need to be replaced.
By 100,000 miles the ignition key tends to wear out and should be replaced or it may not work as well in the door locks or ignition switch.
It is important to regularly check the valve clearance as the exhaust valves may become too tight. This will lead to valve failures which are expensive to repair.
The power steering pump and power steering hoses tend to develop leaks and require replacement.