I do alot of highway driving and have >100K miles. Everything was running good and I decided to change plugs and wires. I also had to replace the battery. Now I get intermittant hesitation while driving. slight misses especially when when holding a steady 45 MPH. Sometimes no hesitation. When I rev up the engine it doesn’t run smooth. Not sure if there is a RPM limiter on the engine. Engine light is on. Nothing else has ever been replaced. Is there a fuel filter?? Ran fuel injection cleaner through it and everything is the same. Not sure where to start.
Sometimes, one will think that the spark wire terminal has snapped on, when it hasn’t. To help to get a better feel (literally) of when the spark plug wire terminal snaps onto the spark plug, use a silicone grease on the inside of every boot. You can get a tube of silicone grease from an auto parts store, or Radio Shack. Use a q-tip to apply the silicone.
Go to an auto parts store and ask them to read the codes for the check engine light; then, bring them here for advice on next-step.