I agree with this, the bike and wheels have nothing to do with his problem, some people just dont have it. Some people just ride 53x14 for years and suddenly after the year #4 they start wondering why instead of getting faster they got slower and slower.

Too many things to mention, but the op should start describing candence he use, gears he use, etc etc because there is no way to know what are u doing wrong.

The saddest part for some riders is that they simply suck and not even training they will improve that much. I have seen and raced with people like that too, just givin' my opinion ok?