The IS 300 may have several common problems.

One issue could be related to the engine. Sometimes, there might be performance fluctuations or unusual noises. This could be due to problems with fuel injection systems or engine components wearing out over time. The solution might involve regular engine maintenance, including timely oil changes and checks on the fuel system.

Another common problem could be with the transmission. Shifting might not be smooth, or there could be jerking sensations. This could be caused by issues with the transmission fluid or internal transmission components. Regular transmission fluid changes and inspections could help.

Electrical problems can also occur. For instance, malfunctioning dashboard lights or issues with the car's electronics. Checking and maintaining the electrical system, as well as addressing any faulty wiring or sensors, could solve these problems.

Suspension problems might arise too, leading to a bumpy ride. This could be due to worn-out shock absorbers or other suspension components. Replacing the worn parts and getting regular suspension checks can improve the ride quality.