Toyota Repair: Engine hesitation, electronic fuel injection, vacuum hoses

Question
I own a 1998 Toyota Corolla with 70,000 miles automatic transmission,and electronic fuel injection. Upon acceleration the engine hesitates and bucks. I thought it might be the fuel filter but since they are meant to be lifetime filters that is not the issue. As far as I know I have not purchased contaminated fuel. What else could it be? This has been a great car with no other problems.  

Answer
The most common cause for this that there is an intake system air leak, check the large intake air hose from the air filter to the throttle body for any cracks or loose clamps, check for any vacuum hoses that may have become disconnected.
If there is not a vacuum leak I recommend that you replace the spark plugs, the plug wires, the distributor cap and rotor, it sounds like there may be an engine misfire under load.