Grab some WD-40 and spray it on some of the pulleys. I had the same sound, it is my air pump. Let me think aobut the idle, I had that issue with my 2.6, let me see if I can remember how I fixed it.


'90 Trooper - 2.6L 5-Speed - 1" BL - Custom Roof Rack+2x55watt ProComp - Herculined Interior - Pace Setter Header - Dynomax Super Turbo - K&N - ProComp ES3000 Shocks - Optima Red - MSD 6A - 31" Kumho Mudders - Black Rock Crawlers