Have new plugs and the wiring harness looks fine so either it was replaced or is new enough.
Engine starts perfectly but idle will drop for a second several times per minute. Sometimes less, sometimes more.
When car is in gear and this happens the engine will shudder a bit as if a load has been put on it (transmission?). In neutral you can barely notice the idle drop.
When driving and accelerating strongly or even up a hill the engine runs quite roughly and there isn't much power.
Problem is intermittent but getting worse. There are certainly times where I can floor it at 30 and fly effortlessly onto the freeway. Othertimes the car struggles to go up a hill at 25 mph.
New variation is a snap or popping sound from the rear of the engine or front of the transmission.
I think I might have to take this one to the shop...