Re: Why does my diesel not rev when in gear?
Don't worry about flooding diesel engines don't flood. The fuel air mixture doesn't ever prevent combustion in a compression ignition engine.
Sounds like a throttle linkage problem as was said above or a problem with the governor on the engine. Try to find out what moving parts control the governor and see if anything there is getting stuck. Maybe the throttle output of the governor is getting stuck and not going over a certain point.
The starting thing may be related to having the throttle stuck at a low position and not putting out enough fuel when the fuel pressure is low during starting, but then becomes sufficient to run the engine once the injector pump comes up to full pressure. Or it could be the injection system or engine is wearing out.
If it cranks for a long time and then catches and starts suddenly it's more likely low compression. If it cranks for a long time and starts to fire a tiny bit and then a little more and a little more and slowly gets enough power to run without the starter then it's a fuel system problem.