1985 Ford Crown Victoria ECM

Engine Mechanical problem
1985 Ford Crown Victoria V8 Automatic 125, 00 miles

I bought a 1985 Crown Vic a few months back and it has started to run terrible when it is at operating temp. I brought the car to a shop and was told the there was to many emissions sensors missing to do a diagnostic test. The car ran like a dream when I first picked it up and tried to tell the shop this, but they had no clue to the reason. They also told me that they could not do the diagnostic on it because the check engine light didn't come on and all this after having the car for almost a week. I responded that the light is more than likely burned out and they were still stumped (I had to laugh and asked myself how this place stayed in business). So since then I have replaced the coil pack, pick up coil, fuel filter, fuel injectors, ignition control mod (also relocated it from the distributor to the fender wall), temp sensor and the o2 sensor. After replacing all the components it still runs the same way when it reaches operating temp. Now I am wondering if it might be the ECM, since the car runs great when it is cold and the ECM is in open loop. So my question is, is there a way to trick the ECM into running in the open loop all the time so I can see if it is the ECM before I go and spend another couple hundred dollars on a car that has past it's value in repair costs. I would aperciate your help and input.