Your code reader(s) may not work because your car is probably OBD1, and OBD2 readers will not work on it - so not reading any fault codes on your OBD2 reader does not mean there are no fault codes
Cleaning the EGR valve is literally a waste of time - best to get a solid EGR blanking plate fitted, and clean out the inlet manifold. especially as you have a Euro3 Mondeo if the year on your profile is correct
There are different types of 2.0L 130s, yours is probably a Euro 3 with pnumatic actuator and front EGR, but some pictures would be useful to confirm
The glow plug light flashing is used as a warning for many reasons - it does not nessisarily mean the glow plugs are faulty
How much did the injectors cost? were they new/refurbed/secondhand? how did you (re)code them?