1990 Ranger 4.0 Codes 41 & 42

Hi,

I have a 90 Ranger 4x4 with 4.0. When I run the dianostics (KOER) I get trouble code 42. Then when I clear the codes and drive the truck till I get the check engine light, I get the trouble code 41.

Lean & Rich? What's Up?

What should I look for?

Thanks!

For those interested. The problem was the fuel regulator. At start up it ran the fuel pressure at 30 or so, then 90psi. Changed that and all is better.