I don't have an answer, I am commenting because it's strange to see a description of a problem so like my own. You would assume that 1 person would either have erectile dysfunction OR premature ejaculation issues, rather than somehow suffering on both ends of the spectrum. But I run into this problem quite often. To me, it almost seems like it's more sensitive when it's not completely hard for some reason.

For me, such issues have been very on and off to varying degrees. For the lasts 2-3 years forplay always kills it for me after a minute or so, so I always keep that to a minimum. I used to love forplay... oh well... I also like to be in control. That helps. I don't really get into sex unless it's initiated by me. A girl asking for sex or telling me how to fuck her (harder/softer/faster/slower) turns me off. Always has.