For the Level-D connaisseurs

Good day all of you,

I've been trying to work around a problem I'm having with the LDS 763, but I can't seem to get around it; Step Climbing.

In terms of fuel management, on the long hauls it pays off to fly the optimum FL.

Now I'll occasionaly do a transcontinental flight from say Amsterdam to San Fransisco, Seattle, Panama etc. and (yes, bing on the flames :p) I'll close my eyes for a few hours over the atlantic.

However, whilst asleep obviously Im not able to perform the step-climbs manually, and I can't get the FMC to do it.

Does anyone know if it is possible first of all?

Secondly, let me work out the scenario quickly, perhaps someone spots what I'm doing wrong.

I'm taking off, Crz FL set to 390, MCP ALT set to 39000 (Or 380/38000 depending on where I am going). During climb, LNAV/VNAV are engaged and the plane accelerates, then maintains the attitude required to maintain the VNAV ECON speed.

On the LEGS page, altitude restrictions are entered, say

FIX001 m.803/fl310
FIX002 m.804/fl350
FIX003 m.806/fl390

Then, when reaching FL310, the A/P enters VNAV PTH mode, and will maintain FL310 until passing FIX001.
It then continues climb in VNAV SPD, but instead of climbing to 350, it goes straight through to 390.

Can you get around this without manual interference?