Throttle Position Sensor fault?

Could any of the experts on here help with this one please? My 2003 Disco 2 TD5 "hiccups" under a part-throttle. Not all the time but enough to be worrying. Occasionally it's so bad that the M+S green lights come on and the thing goes into limp mode. However, switch it off, give it a minute and it'll restart and run OK for a while.

Oddly, it runs perfectly OK when using cruise control, even when holding the set paddle to accelerate. Runs like a train in fact. This would seem to suggest the accelerator's Throttle Position Sensor is at fault and causing the hiccup.

Does that sound like a reasonable diagnosis or am I being too hopeful that it's that simple?

Cheers!

the simplest way would be to read the fault codes stored in the transmission ECU...by the way is your battery in good shape?

a throttle position sensor failure would make it missbehave stationary/out of gear too... try it so, and if the revs will have failures while you push the throttle this way(do it gently then harder too) it leads closer to a TPS failure... but only the tester will give you a certain answer