If you are running that rich you probably have fuel diluted oil that has washed down the cylinder walls which will lower compression although there may be other causes.
Causes of running Black Rich...
1)Spark Plug Fouling
a)If all 4 spark plugs are fouled continue to step 2.
b)If only one or two are fouled, post back.
2)Fuel Pressure
You already determined that Fuel Pressure is OK...
a)When you shut the engine off did fuel pressure hold or drop quickly/suddenly, pressure should hold for anywhere from 15 - 30 minutes after the engine is shut off.
b)If pressure drops quickly/suddenly, post back.
c)If pressure held there are no leaking injectors.
3)Map Sensor Circuit or Loss Of Engine Vacuum
The MAP Sensor is the Dominant Fuel Control Sensor (The Air Charge/Coolant Temp sensors play a minor role and the O2 sensor is only a fuel trimmer) on the vehicle, it looks at the difference between Atmospheric and Manifold Pressure to determine how much air is in the engine and the controller uses this information to calculate Ignition Timing and Injector Pulse Width.
When engine vacuum drops that indicates to the controller that more air has entered the engine and it adds more fuel.
If engine vacuum is low due to an engine problem such as Low Compression, Cam/Ignition Timing being incorrect (which will cause low compression) or a Restricted/Broken Vacuum Line to the Baro Solenoid or Map Sensor then you will run rich.
a)What is engine vacuum reading at a manifold source?
15 - 20" HG is the normal range, below 15" HG you are low and will have to determine the cause.
LINK-
www.secondchancegarage.com
b)If engine vacuum is low then start by verifying Cam Timing is correct.
This seems to be a major area of confusion and time lost during install or diagnosing as to weather the Cam is truly aligned properly. There have been numerous threads over time that the OP said the Cam timing was verified to be correct (checked it 3-4 times) and after a 4 page thread and...
www.turbododge.com
b)If engine vacuum reads normal at a manifold source tee a vacuum gauge into the vacuum line between the manifold and Baro solenoid, is vacuum reading 15 - 20" HG?
IF OK...
c)Tee a vacuum gauge inline between the Baro solenoid and the Map sensor, is vacuum reading 15 - 20" HG?
If OK...
d)Check Map Sensor Calibration
I am posting this so I do not have to keep typing this over and over and will make it easier for members to find help on their own. Fault Code 13/14... No Change In Map Voltage From Key On To Engine Start Map Voltage Does Not Equal Throttle Position. Map Voltage Low Map Voltage High Map...
www.turbododge.com
4)If all 4 plugs are fouled, fuel pressure holds when the engine is shut off, cam timing is correct and there are no restricted/broken vacuum lines between the manifold/baro solenoid/map sensor but engine vacuum is low and you have low compression you will need to determine why compression is low.
A Cylinder Leakdown Test will tell you where the loss of compression is coming from.
Before performing another compression test and a cylinder leakdown test remove the fuel diluted oil and filter from the engine and get fresh oil/filter in the car. (Any 10W-30 Dino oil will do)
Disconnect/remove the ASD Relay (on a 91 it is in the PDC and should labeled "Auto Shutdown Relay") and crank the engine 10 - 15 seconds to get fresh oil into the cylinders and other vital parts.
LINK-
Before you tear down the engine, pinpoint where problems are by using these three steps to do an engine leakdown test.
mobiloil.com
1991 Daytona ASD Relay Location
I am not home on weekends but I do check my phone once in a while should you need/require more info/assistance.