Right now we are not going to concern ourselves with previous repairs, we are going to focus on the fault codes and then proceed from there if you are still having issues.
If the power loss/check engine light is illuminated then the car is in "failure/limp in" mode meaning that there is a "hard fault", when that happens the engine controller brings ignition timing to "base" and turns on the cooling fan for safety reasons.
You need to start by diagnosing and repairing the fault codes that are stored.
You always start with the lowest number code which may be causing the other codes, repair that, clear the codes, run the vehicle and see if the others come back.
On a 86 the engine controller is not very smart and "limp in mode" only allows the engine to barely run on basics to get to a repair facility.
As controllers evolved they got smarter and if the CEL came on (depending on the actual problem) you may not even notice a difference in running condition.
CODE 21 OXYGEN SENSOR CIRCUIT
Fault Code 21
Probably a bad O2 sensor, a non-heated, single wire O2 sensor has a life expectancy of about 50,000 miles but if t is contaminated by other chemicals such as coolant it may/will fail sooner.
CODE 22 COOLANT TEMP SENSOR CIRCUIT
The voltage from the CTS is high (open) or low (shorted).
Backprobe the CTS connector with backprobe pins (paper clips will work) and connect a digital voltmeter and see what the voltage is reading, if the voltage is not correct replace the CTS.
If it is correct at the connector then further diagnostics are needed.
CODE 52 RICH EXHAUST INDICATION
Code 52 means that the oxygen sensor voltage is latched above .450 volts (rich) and the controller fuel adjustments have failed to get the voltage to change.
This code is probably being caused by the code 21/code 22.
Depending on how rich you are running right now you may have to clean/replace the plugs again if they are fuel/carbon fouled and change the oil/filter again if the oil is fuel diluted, pull the dipstick and smell it, do you smell fuel?
The Cat may also be causing driveabilty issues if it is restricting exhaust flow, if you are still having issues after we diagnose and repair the fault codes then I would recommend replacing the cat as the next step.
Any questions/concerns/problems Please
feel free to ask.