I have a new to me 03 Disco, sounds great, looks great, went ahead and had my mechanic put in a rebuilt front drive shaft. One questions, when I idle at a light, it seems the truck has a intermittent very very subtle tremor , like every 5- 8 seconds or so and a very quiet what sounds like a valve tap on occasion. No warning lights, temperature gauge hasnt moved at all, but I just want to be cautious. Any cause for concern, could this be caused by the new driveshaft?

 

When idling at a light there is no part being played by the driveshaft at all. Fuel injector cleaning or even intake cleaning would be my first step.