FIXED!
Replaced spark plug wires and boots. The boot for plug #4 wasn't seating properly on the plug. The "snap" was weak and it would easily pop off, yet still resting in the spark plug hole would make enough contact for idling and low throttle operations (strangely, and high RPM / full throttle too). Apparently, over 17 years and 100k miles at some point the metal connector inside the boot got deformed.
Now it runs like new again, smooth at all RPM and throttle settings.
Now with the clean UOA (head gaskets OK), new timing belt, pulleys, water pump, t-stat, coolant flush, fuel filter and plug wires, this car is ready to go another 100k miles.
Replaced spark plug wires and boots. The boot for plug #4 wasn't seating properly on the plug. The "snap" was weak and it would easily pop off, yet still resting in the spark plug hole would make enough contact for idling and low throttle operations (strangely, and high RPM / full throttle too). Apparently, over 17 years and 100k miles at some point the metal connector inside the boot got deformed.
Now it runs like new again, smooth at all RPM and throttle settings.
Now with the clean UOA (head gaskets OK), new timing belt, pulleys, water pump, t-stat, coolant flush, fuel filter and plug wires, this car is ready to go another 100k miles.
