This 2003 Toyota Rav-4 came in with an engine hesitation and with the engine mangement light on.
We carried out a diagnostics test and found immediately that the number four coil pack had failed so therefore causing the engine to run on 3 cylinders instead of all 4. This failed coil pack had caused the engine to hesitate.
Whenever this happens to an engine we always replace the ignition coil pack and a the complete set of spark plugs. If you replace one without the other the fault is likely to happen again.
So with the spark plugs and the coil pack replaced the engine ran absolutely fine with no hesitations.
A simple job to diagnose and relatively straight forward to fix.