Had a bad stumble at idle and accelerating!

What is your question?

Had codes 300 & 307.changed plugs,cap,rotor,coil.wires are ac delco and only year old. No help. Then found out it had bad injector. Had the spider type. so put in the new mfi injector. This helped a bunch. But still has just a very little stumble at idle and giving it gas. 161000 miles.I think its just old and things worn out!