Is the check engine lamp on? I would like to think it would be, but I have seen some serious engine problems that did not illuminate the MIL ( malfunction indiactor lamp ) in the past. Checking fuel pressure is always a good idea, I personally like the clogged exhaust theory off the top of my head. From your short description, what stands out to me is that you specify 3000 rpms. Clogged, or should I say restricted exhaust systems tend to make the efficiency of the engine much worse at higher RPM's due the the amount of air trying to flow through it. I would be even more suspicious of a restricted catalytic converter if you have had any repairs made in the past or recent past for cylinder misfires.
Some more details about the vehicles current state of affairs and recent repair work would help out. How many miles, typical driving conditions for the vehicle, anything helps.
Also, the mass airflow ( MAF ) sensors on Ford vehicles have a very large influence on fuel control, and when they get excessively dirty can cause symptoms similar to your description, but I can't say that I have ever had one stall or get close to stalling because of a faulty or dirty MAF. The typical main concern with a MAF problem is lack of power.
Good luck to you, ask more questions if you need.