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Q:

wha is the timing? on 1994 GMC Vandura 3500

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
when i goin the the hiway and is an slope , the speed go down drasticly from 65 to 35 mph., lus power..
(1) Answer
sounds like a clogged cat converter. take it to a shop for a check to verify and a bid for repair.

Roy