2000 Elantra CEL (misfire cyl 4), occurs with heavier throttle
 

I took a road trip this weekend about 700 miles total, got gas a couple of times in South Carolina at big gas stations/truck stops, car ran great. I did drive it a little hard, 90mph on interstate, but no issues. Monday got to work no problems but then when out to lunch I slowed for a car making a turn and when i stepped back on the gas my car stuttered and CEL came on blinking. It seemed if i got it up to 2500 rpm or more it ran ok and the CEL stayed on solid but then if i slowed or stopped the car would stutter and CEL return to blinking. Tuesday went to parts store and stutter seemed less and really only when heavier on the gas, if i took it real easy no stutter. I bought spark plugs and wires but have not put them on yet, hoping for some opinions first. I did have a similar occurrence 4 or 5 years ago and the shop just replaced the plugs and wires to fix it but i don't recall the exact behavior of the car at that time. Also bought a can of sea foam fuel system cleaner and have not put that in the tank yet either. Any thoughts would be great. Thanks.

YES!!!! I changed the plugs and wires and disconnected the battery to clear the code and it is back to running normal.