It's hard to troubleshoot something that isn't giving you a fault. If you suspect the egr valve and it's not to expensive I would say change it. If that doesn't fix your problem I wouldn't continue to throw money at it. Either drive it as is until it gives you a code or take it to a shop...
Woops, I was thinking 93 like mine haha. Well if it is a coil pack, do a resistance test on the new one you just bought and compare that to the rest of them to see if you have another bad one.
It would have to be ford for me. I have a 93 f150 4x4 short box with 260k hard miles on it and still runs fine. Last year I bought a new fx4 loaded (except ecoboost) absolutely love it.
Maintenance is key to make anything last longer, so make sure you look at programs they offer if your not...