'91 Explorer
 

4.0 liter V6. Taking off it hesitates for about a 1/2 second and then is fine. Drives fine when going down the road until I hit a bump and hit hesitates slightly again. I've just changed plugs and wires. I've ran a tank of injector cleaner. I am getting ready to check fuel filter. Anyone else had this problem? What does this sound like? Fuel/air delivery? injectors, filter? or something else. Transmission seems alright. It does have 170k miles.
Thanks

My guess would be the fuel filter. Especially if you hit a bump and it messes with the motor. You might check and make sure your spark plug wires are ok and not shorted out against something like a header or valve cover.

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1994 Red SVT Lightning #2019