I started my tune up on my 89 DLX 4x4 with the 22RE today, and the back to plugs came out all most white, with the very rear one nearest to the fire wall being the worst of the two. The front two cam out a nice toasty brown color.

I have a low end stumble, and a miss at idel, and with the color of the rear two plus, I'm thinking I have a vac. leak some where.

Any hints on where to start looking??