This article is from the Chrysler-Plymouth-Dodge FAQ, by Dr. David Zatz with numerous contributions by others.
George Lobay's 2.2 TBI had poor gas mileage, poor cold starts, and codes
17, 22, and 52. The cause was a bad connection in the circuit to the
coolant sensor, causing the computer to guess the engine temperature (high
idle). The cure: cleaning near the coolant sensor connector, on the round
6-position connector in behind the battery; and on the bulkhead connector
on the driver's side. Then check voltage at coolant sensor (leave it
connected, just skin a bit off the insulation of each wire and tap in with
your multimeter) it should be somewhere in the 3 Volt range. If that
doesn't do it the only connector left is the one on the computer. Note:
don't forget that if you remove the computer connector you must re-grease
it by Chrysler procedures.