My wife is reporting an intermittent problem with our '98D1 petrol V8. 3 or 4 times a week when driving (engine warm) the rev's will suddenly drop to around 1k for 2 or 3 seconds then increase then drop again then everything is fine (haven't experienced it myself). I suspect something with the fuel system but not sure. We run it on 95 or 98 fuel. Any ideas?

 

I bet your VSS is failing. It may think you're going too fast and cut power to one bank of cylinders. If you have an ultragauge you can look at the mph live readout to see if it's faulty. I've had this happen.

 

Thanks. I'll swap it out and see what happens.

 

TPS is bad, there was actually a TSB on this issue.
Replace your throttle position sensor.
It is dropping to idle speed.

 

Swapped the VSS but the problem remains. Will try the TPS and let you know how it goes. Thanks for all the help.

 

If revs might be going to zero on tach but still actually turning those rpms on the engine consider a bad alternator.

 

Its a bad TPS, like I already told him.

 

More suggestions here. Follow the link for the final answer (I hope).
https://landroverforums.com/forum/di...mystery-53647/