Living here in Colorado I know exactly what you mean. The only real solution is an aftermarket turbo. The NA is a dog but the turbo screams at this altitude.
In th elate 70's I was hitchhiking the shuttle on a Mattawa River canoe trip in Ontario. A young guy in an old 50's Volvo picked me up. It was ratty enough that you had to hook the seatbelt thru the door handle and latch the belt to hold the door shut. Between the front seats he had a pump oil can with a hose going up under the dash. I asked him what it was. He replied, "Proximity Regulator." I pondered for a while about such a device. I finally asked him, "What does it do?" He said, "Watch this." He slowed down until someone started tailgaiting. He then gave the can a couple of pumps and a big cloud of blue smoke emerged from the tailpipe. He had the hose directly plumbed into either the intake or the exhaust manifold and he used it to give obnoxious drivers a good dose of smelly oil smoke. Very creative.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13