Check Engine Light 1986 Crown Vic

Greetings, I had made contact last week regarding my 1986 Ford Crown Victoria. As mentioned before I have recently had upper engine gaskets replaced, new plugs/wires/rotor and cap.
After repair work was completed my check engine light would come on whenever I brought the car to a stop and during idleing. When I start to drive the light goes off and remains off until the car gears down and come to a stop.
You had recomended to have the computer scaned and I did.
The following codes where read
PO14:Profile ignition pick up erratic
PO12: Cannot read RPM
PO14: Exhaust gas not circulating. Lean Exhaust (Bank1)
I have checked my vac hose going to my EGR valve and didn't find it damaged or clogged. I also replaced my EGR selinod without any resolve.
I'm wondering about the EGR itself but haven't replaced because of the costly expense and lack of abitlity to know how to test it.
Could this lead to a check engine light on an 86 Crown Vic? The owners manual states that check engine light usually means low oil pressure ( I have had the oil pressure senor change ) or coolant temp to be probable causes. Coolant is topped up, the car seems to run fine on the highway but when I'm coming to a stop it seems a little rough and the light comes on.
Any suggestions I might have my mechanic look into? Thanks, Mac.