I have a 1995 Fender Hot Rod Deluxe, it's one of the first 500 ever produced (so I was told my an amp repair tech years ago).  After years of it collecting dust, I have been gigging with it 1-2 times a month for the last 6 months.  It has had a recurring issue that I find very odd, and even an experience amp tech does not seem to be able to diagnose is.

What happens is while I am playing, always at least 30-45 minutes into a performance, it will suddenly cut silent.  This ONLY happens when it has a lot of gain going through it.  For example, the second I hit my tubescreamer pedal the sound will cut out, or as soon as I hit a really high note with the amp's overdrive on.  It generally will come back on after about 15-30 seconds, and this will happen maybe another 1-2 times throughout a performance.  During my last performance, the sound did NOT end up coming back, even when I plugged in directly, however it once again worked fine when I got home.

What the hell could be causing this?  I brought it in to an amp tech, he said he was not able to recreate the problem.  Does this have something to do with my pedals?  How/why would the pedals affect the amp like this?  Any insight is appreciated as I am clueless and I am afraid it is going to crap out on me for many gigs to come.