I keep killing o2's
 

I have a full bolt ons, cam only lt1 formula 97 (obdII)
The cam is a GM 845 Specs are: 214/222 .520/.543 112

I am assuming that the reason I keep throwing o2 sensor codes (check engine) is because I am getting inadequate fuel.

Any idea if this is a good estimate, what else might I check?

I have noticed a slight drop in MPG, could an injector be stuck open?

So it's untuned?
Any exhaust leaks?
Running rich?

The exhaust has no known leaks, I guess I could start off by tightening the header bolts again, they do have a habit of becoming unsprung

Yes it is untuned for the time being

Try and fix simple things fix and then go with a tune and see what happens