Fuel pressure on the TBI is 14-16 PSI.(AN Body TBI is 39 PSI)
They make an adapter hose that would go between the fuel inlet and TBI that has a service valve on it to attach the gauge.
Engine vacuum at a manifold source and at the Map Sensor @ idle should be 16-20" HG and steady.
When looking for the causes of Code 51 look at all of your basics first and verify the O2 sensor is not at fault.
The average life of a HO2S is 60K.
1)Physically inspect the wiring to be sure it is not damaged causing a short.
2)Backprobe the O2 signal line at the O2 connector BK/DG wire(do not confuse with the DG/BK) and read the voltage.
A properly operating system O2 voltage will constantly cross above/below .450 volts.
With your Code 51 voltage should be latched below .450 volts.
3)If this is the case create a rich condition by goosing the throttle several times and see if voltage increases above .450 volts, if it does not replace the O2 sensor.
4)Also be aware that an exhaust leak before the O2 adds additional air to the exhaust stream and causes the O2 to latch below .450 volts.
If the code persists after checking/replacing the O2 other causes and items to check...
1)Cam/Ignition Timing
2)Spark Plugs for wear and fouling
3)Excessive resistance in secondary ignition, Cap, Rotor, Wires
3)PCV System operating properly, hoses not soft/swollen/collapsed/cracked/loose fitting
4)Vacuum System, hoses are tight/secure/NOT cracked/dry rotted/swollen/collapsed.
Of course this is all on the assumption that the engine is in sound mechanical condition.
Your hard start condition when cold may be caused by one of the above conditions and/or a carboned throttle plate and AIS pintle.
CHECKING CAM TIMING
http://www.turbododge.com/forums/f4/f14/359212-cam-timing-belt-tension-84-95-a.html
