After re-connecting and fixing my EGR valve and system i have been noticing a slight backfire right after shifting.......The engine has 210000 is very well maint. and freshly tuned up.......i ran it for years with the egr valve disconnected and never had this pop...also the cat has been gutted for like 10 years and i never had any backfire.....the thing always passed inspection with the gutted cat and the egr valve disconnected...... But i would notice on the inspection the nox levels were always close to the limits.....so i decided to replace and re connect the egr system........My question is should i just disconnect the egr system ?? or Do you guys think it is starting to develop other problems due to age and wear to cause this backfire?? ....I have notice some timing chain rattling that i have not fixed because i am still debating on re-power it or rebuilding ect....... What are your experiences running without egr system???