Land Rover Repair: Stalling, rough idle, throttle position sensor, cylinder lubricant

Question
We have a 1994 RR Classic. 92,000 miles. Runs GREAT at cruising speed, anywhere between 25mph - 70mph. Like a champ. VERY rough idle, acts as if it will die at stop lights. Almost always dies going slowly in reverse. Has died at stops, we just simply shift into park, and it starts right back up. Things done recently by a certified RR specialist: replaced dist cap, rotor, plugs and wires, reset timing and idle. Replaced both O2 sensors. Replace throttle position sensor. By passed the heater core due to leaks, and replaced water pump.

It bogs down worse than ever. Any ideas?

Answer
It does sound like a tune-up issue.  If the base idle is set correctly and the tune-up has been performed correctly, have the fuel pressure checked and see if it is in range.  If fuel pressure is off, replace fuel pump and/or filter.  Also, make sure the engine is getting up to a correct working temperature and the thermostat is not stuck open.  Lastly, at 90k+ miles you may have carbonized valves (very common at this mileage).  Add an upper cylinder lubricant to the oil to free off sticky valves, rings and lifters.  You could also have an upper throttle body injection service, which will decoke the valves.