Hi, have recently purchased a TR 1993 Magna v6 Auto and I am getting 15L/100km with very sedate driving. The person who I bought it off of said it was very economical! What a load of BS!
Facts:

It idles at 1100rpm.
stumbles a bit on idle occasionally
Exhaust smells rich
I think it runs a bit too hot
Engine timing retared to 20 deg BTDC at idle @ 700RPM ( I adjsuted throttle body screw to reduce the idle speed for this test
Engine is other wise in very good condition - quiet, quite good performance when pushed, no smoke from exhaust
Checked for idle-up AC is activated - nil.
Plugged and unplugged idle motor, no difference in RPM at idle

I have little idea on what would be causing this? ECU fault, AFM, Coolant sensor, Oxygen sensor, Ignition system, who know?

I don't want to spend heaps of money at the mechanics on this problem so I thought I will try and investigate and I would really appreciate anyone's input.

Cheers,

Start off my adjusting the ignition timing to the correct setting, using the method in the manual. Then replace the ISC. Check TPS setting.

Thank you for the reply MadMax. I filled up today and I got 13L/100 on the last tank of fuel, still a bit high, and I haven't altered anything yet. I will now have to purchase a workshop manual to check the ignition timing etc. to understand more about the magnas. I am also going to start from scratch before adjustments and replace plugs, ignition leads and change the oil.

If after doing the things MadMax suggested the exhaust still smells rich, check the oxygen sensor. If it has failed it will force the ECU to run the engine rich.