Hope this comes out right You _think_ it is too lean, just like the computer _thinks_ it is too lean because that's what the O2 says. But... If the O2 is way off, it will read lean with the correct ratio, it tells the computer 'lean' so the computer adds more fuel, end result, rich running, not lean running. Either way, if that new, probably OK.

Agreed, could be coil yes, normal test is a 'how far the spark jumps' test but that doesn't take into account heat breakdown or high rpm break down. It's probably OK.. Make sure there is no tracking inside the cap too. Again, it is harder for a plug to spark under certain conditions in the combustion chamber so at those times, the spark can jump easier spots like carbon inside the cap but jump the plugs when it is easier to do so.

Either way, yes, I think you are into more than a spark problem but you do have to cover the basics off first. Next basic beyond spark is fuel flow and pressure. Simple plugged filter will cause a big drop in pressure at high rpm (high flow) and have no effect at idle when only small amounts of fuel need to get through. You have a filter screen in the tank and a normal filter under the car. A pressure gauge on the rail will tell the story there, but they are not that cheap and are a seldom used tool. Trial and error is only other way for fuel flow (new filters etc)