95 Astro not running smoothly hiway speeds

[rfloyd]

1995 Chevy Astro 143000 miles. Was traveling on the highway and pulled off to a stop sign. Engine started to run rough, and service engine light came on. My mechanic said it was the EGR valve and was replaced. Van seems to run fine in town but at highway speeds I now feel a hard deceleration in overdrive. Almost feels like the A/C compressor is turning on and off. Problem still exists with A/C off. Notice the problem more when on level road or going down slight hill. Never feel any acceleration just the deceleration. I feel this every 15 to 30 seconds at highway speeds. Mechanic said it was probably the Torque Converter, they flushed the transmission. But problem still exists. If the replacement EGR valve was faulty, would it cause this problem? Thanks in advance

[GMMerlin]

usually on these engines its not the valve that is the problem but the chunks of carbon that get stuck in the valve.
Sometimes these chunks can cause damage to the valve.
When I replace an EGR valve on those engines, I use a "kleen screen" gasket from Tomco..this prevents additional cabon pieces from entering the valve.