Been a long time since I flew a long haul so I hopped in my 744 and took off from KSFO to Kansai Intl via some intersections..

Takeoff roll fine, climb fine.. to about FL290..

Number of things went wrong above 15000.  EPR started dropping, as did airspeed..  There were no options on the panel to do anything about the EPR.

At FL290, at a fpm rate of 1500, I was going at 200KIAS with an EPR of .87. N1 at the time was 95.7, and in fact, it was around 95.7 throughout the climb.

I get to FL310, at 1000fpm, .61MACH, EPR of .82, N1 the same..  level at FL350, .60MACH, EPR of .84, N1 the same..  I had full throttle all the way up..

Winds were nothing, altimeter normal, no clouds (basically perfect weather).

THEN, about five minutes later, the EPR starts crawling back up.  .86 EPR, .88. EPR, .61mach , .62mach.  Five minutes later, I was .89MACH, overspeed at FL350, EPR all the way at 1.5.  Finally the Mach hold kicked in and it dropped and held at .85 M, and EPR holding at around 1.35.

Now I ask you, WHAT HAPPENED TO THE POWER?? THE BITE!?