battery light, only at high revs?

ive had this prob for about a year now. only when the car revs more than 5000, the battery light comes on. then shfts really hard. loss of power just for a sec and all lights dim. new belt, alt and battery. had a diagnostic performed only to say nothings wrong?garage said maybe chip but this has been going on for a little over a year.(car has good ground, no burnt fusses). hlp please

You have a real problem there. Only thing I can think of that can cause that problem is your belt tensioner is weak and when you rev it that high, it looses its tension and does not turn the alternator. Check it out.

checked that last week when i changed the belt. tentioner is tight