Need a little help Cummins

I have a 2001 Ram 2500 cummins diesel. The past few days (with no check engine light) the truck seemed to go into some type of limp mode very similar to newer duramaxes. Upon first start up when I try to drive the truck it wont go over 2000 rpm and has llittle power. If I shut it off and restart it. the truck runs perfect with full power. Any ideas what this might be

Yep, mine did the same thing right after making a fair sharp right hand turn. After taking the TPS/Accelerator Pedal Position Sensor(APPS) loose, disconnecting & re-connecting it several times, mine quit doing it for a year. When it started doing it again a year later, I did the disconnect/re-connect drill again.
Turn your keyswitch on-off-on-off-on then look at your odometer for trouble codes...some will not turn on the Check Engine light.

I will give it a shot and see what happens. Thanks

A lot of people describe the same situation when the limp pump is going out.