This is an off topic question about my truck. I hope you don't mind me
tossing it out here as you guys are plenty sharp and helpful.

It's a '98 Silverado Z71, 5.7L, 4x4, K1500, automatic. I have had the truck
since it was new and it still runs great at 99,000. Yesterday all at once
the ABS light came on, the speedo quit working, and it seemed like the
tranny was jumping in and out of gear. Just as suddenly it all went away and
the truck ran fine again. I thought I felt a light activation of the ABS at
very low speed as I was stopping when I got home. I got a P0505 on the OBD
(Idle control system malfunction).

Any help will be appreciated.

Thanks.

Jim