I have a 91 F-150 with a inline 6 cylinder and it has a terrible miss in it. It does it at idle and when youi tap the gas lightly the engine RPMs will actually drop instead of going up. I have put new plugs, wires, cap, rotor, module&stator in the distributor, new coil, new Trottle Positioning Sensor, throttle body cleaned, new gasket too, sprayed the intake and all vacuum to check for leaks and still nothing, if anyone knows anything or has any suggestions, please email me. The truck has 110,000 miles. Any help on this would greatly be appreciated, its been going on for months and i cant seem to fix it. Please email me at jason@jdmautomotive.net