i loose my erection just before ejaculation but i am able to keep it for long periods of time

Sounds like you're getting exhausted.  You can't maintain an erection when you are so distracted by tired muscles/shortness of breath etc.  You need to go excersize.  Hit the weights and treadmill and you'll be fine.

i am 47 and just last week for the first time am going through what you are going through, i was freaking out a little bit , but after talking to a few friends i found out its not uncommon. i am still going to see my dr. about this first and let him direct me to a specialest from there.i have been having some problems in the last few months , like stress, pain from old injuries, possibly the beginnings of depression, i havent been playing sports for the last few months, maybe out of shape?