After doing some work on my 97 Blazer this past weekend fixing a high speed vibration on a test run down the freeway I noticed a high speed surge in the engine.

I had been reducing my highway speeds because of this noise coming from the rear of the truck but after that was fixed the surge started when my speeds went back to 65 mph. A couple days later this surge had me down to below 60 mph again.

After looking for anyone with similar problems I decided to change the fuel filter that was the original to the truck with 169K on the clock.

Problem solved.....