1998 toyota rav4 insufficent flow indicator?

I have a 98 toyota rav4 that I recently replaced the egr vavle on because my check engine light came on and I went in to run a diagnostics on it and they stated that there was insufficient flow going through my egr vavle. I replaced it and reset the sensors and for a few days everything was fine but I feel that the car still drives rough and by that I mean slower at acceleration then before and also the light came back on. What can the problem be and how can I fix it? Hopefully someone can help.

Rich
November 2007