If you are unable to complete a set of three intervals within certain parameters, your parameters are not appropriate. Making the intervals slightly easier would create a situation where you will be able to finish the workout in a condition where you have enough capacity so that you can push a little extra hard for the last minute or so of the final effort (which is ideal).
You could do try any of the following suggestions:
Shorten the interval length to eight minutes. Once you can complete three intervals of eight minutes with the other parameters remaining as they are, you can lengthen the intervals to nine minutes, then ten minutes.
Change the percentage of FTP for the interval to 90%-100%. Easing back a bit on the effort means you will likely be fresher for the final interval, thus having a better chance of completing it. Once you can complete three intervals at 90%-100%, then you can increase the effort to 90%-105% FTP.
Ride in a larger gear with a lower cadence(the 70-80 r.p.m. with which you are comfortable). In your interval sessions, you are overloading on both cadence and power. It is ideal to overload only one aspect of training per workout (i.e. power, cadence, time on the bike, top end speed). Specificity of training is essential to get the most out of your session.