Strange situation with lean and rich cylinders... Options

[Rockaria]

Hello Everyone,

First off my car runs (seems to run) perfectly. A few months ago I did a spark plug test and all 4 plugs looked exactly the same (Just a little dry black soot) meaning to me a little rich, and just the way I wanted it. As the summer came and is going I started to notice my #2 getting cooler than the #4. At times a difference as much as 60 degrees. I put it as hot weather and the oil cooler on the #4 side. But I recently checked the plugs again and have noticed that #1 and #3 are just like they always have been, but #2 is runing richer than normal and #4 is running leaner than normal.

Any off the hip ideas? I put in a new Fuel injector on #2 thinking that maybe it was old and gunked up and open. But the new injector runs just as rich. Like I said the car does run fine though I have noticed that it is a little harder to get it to idle just rght. Though by adjusting the idle screw it will eventually sit at 850 just fine. The car does not smoke unless I am full throttle (The smoke is mostly dark) and I see no oil on the plugs at all.

Just wondring if anyone had any ideas.

Oh Sorry: it's a 1975 1.8 Stock FI

Thanks,