95 Corolla with EGR Problem?

[Joebowler98]

My 95 Corolla that I bought new has approx 122,000 miles on it. I noticed the other day it started "pinging" when i was accelerating. I had recently bought gas from a place I was unfamiliar with and chalked it up to "Bad Gas". Not but a few days later the check engine light came on one morning when I started it up. I had been really busy and not keeping an eye on it since my wife was driving it. I pulled the dipstick and almost didn't read on the stick! I immediately changed the oil and filter (it was a little over the 3 months but within the 3-4K miles since changed last. I was wondering if that had anything to do with my trouble? I took the car to a mechanic that put it on his reader and said it looked to be the EGR valve but, really didn't seem convincing? I stopped at the local O'Rileys and they said it would be like $175 for that part! The car runs fine except for the little pinging problem. Does this sound right and does anyone have any ideas of things to check? Did the low oil cause this problem? Thanks for any ideas.
Joebowler98