This past weekend i took my 91 K5 on a trip. Everything worked Great all weekend, until i got 10 miles from home. The truck drove 4+ hours (@45-65) down and 3+hours @(55-75) back. Then i got off the hi-way and on the city streets of my town, i started to smell a sweet smell. I was thinking it was some other car, because my truck was not getting hot at all, was not over 180. The floor is dry, and no leaks under the truck. Pulled the dip-stick and not milky oil, no white smoke. I run the Vents on most of the time and do not run the A/C unless it I REAL HOT AND NOT WIND. When I moved the Vents from Floor to Vents, there was a puff of Dust or Smoke and I could smell the sweet smell again. I have not checked the leave of coolant, but I was going to look at it tonight and then drive it on the hi-way and around town and see if it drops. Any one have so ideas on this one? 91 K5 auto, 350, 700, 241, 35s, 3.42, 10b, no top, trany cooler, newer (1year) rad, thermostat(1year), O2 (1year), fuel filter (1year), Plugs(1year).