effects of long term cpi leakage on egr

i just changed my cpi spider and nut kit on my 95 blazer with 75,000 miles on it. it was leaking. see http://www.automotiveforums.com/vbulletin/showthread.php?t=512877 for more info on my situation. i was wondering if i should also change my egr valve because i think my cpi was leaking for at least a month before i stopped driving it. i still dont think im getting the mileage i am supposed to, so i suspect the egr valve.

Normally it doesn't really have an effect on the valve itself. The problems are caused by the chunks of carbon that are formed because of all the raw fuel being dumped into the engine. These chunks break loose and can hang in the valve. The valve can usually be removed and cleaned, it seldom requires replacement. If you didn't clean out the EGR ports while you were replacing the CPI and nut kit, you can expect to have to clean the EGR valve a few times as the remainder of the excess carbon is worked loose.

i still think my exaust smells funny although im not sure. im still getting about 11mpg. what else could be causing this? also would running seafoam through my system be of any benofit at this point? when i removed the plenum i scrapped all the carbon i could see at the egr port and sucked it out with a shop vac.

how should i clean the egr valve by the way?