Hi Scotty, I have a 2006 Mazda 6 I, 2.3L naturally aspirated with a manual transmission. My problem is when I am near the high end of 2nd gear and the low end of 3rd gear the car starts to jerk back n forth. The car had sat for a couple of years so I changed the gasoline to some fresh stuff and a little bit of seafoam. Car still did the same thing so I checked the spark plugs but there was a bunch of motor oil in in the spark plug hole on cylinder 1. I installed a new valve cover gasket and replaced the plugs with new ones even though they looked great and they had white residue. It still did the same thing so I used an ohm meter to test the coils and the readings were almost all the same for all four. I think the engine is getting enough fuel because the car accelerates great in the mid to high RPMs. When I'm driving in 5th gear down the highway the car runs perfectly well. I am hoping to can give me a little help on what I can check next. Car has 300,000kms on the engine and it runs clean with no clicks or anything like that. It eats about a 1/2 to 3/4 of a liter between 5000kms oil changes. Your assistance will be greatly appreciated.
try this cleaning video and pray it helps https://www.youtube.com/watch?v=NWCKvU2FmDc