Thank you very much for your help.
I´ve been measuring with the follower configuration shown on fig 35 in d/sheet and i see it perfectly follows input voltage until 4,2V or so.At that point,op output jumps to 4,5V and stays there.with a load od 220K, output current grows until 19uA,below specifications.
Regarding the amplification figure 36, I see output near zero (tens of millivolts) no matter what input i put, from 0 to 5V.
So, why this BIG limitation as follower?.I must say, i´ve tested with 3 different chips with same result, all chips bought to same eBay seller.