Temp sensor is bad or the idle control valve or ciruit is shot.
What you thought was the choke is the air flow sensor, don't mess about with it, you'll break something.
Make sure the idle control valve is plugged in (small cylinder about half the size of a soda can, two wire plug, two rubber hoses about 1/2 ID). Make sure the hoses are attached, too! Idle speed goes high and stays there in "limp" mode.
If not that simple, you will need a shop, probably, to help you find the problem and fix it.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!