If its just one injector try replacing it. The last number of the code tells you which sensor it is. If its shows more than one more than likely its the throttle position sensor. $35 and 2 screws and you should be good to go.
P0203, injector number three circuit malfunction.
Trouble code P0202 means: Fuel Injector 2 Control Circuit Malfunction
Trouble code P0340 means:Camshaft position sensor circuit malfunction
According to Haynes Repair Manual for 1987 to 1996 Dakota, for 2.5L engines, code 27 means: Fuel injector control circuit. For 3.9L and 5.2L engines, code 27 means: Injector output circuit not responding.
Trouble code P0720 means:Output speed sensor circuit malfunction
Trouble code P0161 means:O2 sensor heater circuit malfunction (Bank 2 Sensor 2)
Trouble code P0205 means: Injector 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 Control
Camshaft position sensor circuit malfunction.Camshaft position sensor circuit malfunction.
Unplugged connector, failed injector, broken wire, bad computer.
Idle speed on a 2000 Dodge Dakota is computer controlled and is not adjustable. If the speed is incorrect there is a mechanical or sensor malfunction.
Engine speed sensor circuit malfunction.
Leaking injector is the most common cause.