Tuning Problems

[manila dave]

I have a 1993 Toyota Hilux Surf with a 2LT diesel engine and automatic transmission. I tried to raise the idling speed up to 800 rpm as recommended but each time I increase the idling speed and shut of the engine, it revs to 1200! I did it several times, even with the diesel mechanic, but still the same. Its now choked at 600-650 rpm but the engine purrs smoothly (engine is not even vibrating) and stable. When I drive and push down on the accelerator, the SUV is accelerating well (except for the smoke which is typical especially in the Philippines where the diesel fuel is not really that clean). Am I doing something wrong or is there something wrong with a part which I can't detect?

Please help. Thanks

Best regards.

David

[TonyN]

if its running ok and idling smoothly why mess with it?