Bringing back from the dead...

So I put in premium fuel, and now it only pings under load (going up hill, accelerating,) in 3rd or higher. I looked at the vac hoses but couldn't see a problem (I actually replaced a lot of them).

When you block off the EGR passage, what do you mean by trash the valve? As in no more EGR passage? <img src="/forums/images/graemlins/confused.gif" alt="" />

87' Raider: off road package, rebuilt engine with (new) stock tires and alloy wheels but otherwise original.