It's possible, although unlikely, that the cam was deliberately installed a tooth off from the factory. If the cam indexed very poorly, they may have moved it a tooth to compensate. However that's gonna be virtually impossible to tell now, unless you disassemble the whole freakin engine and start again.
Does high RPM power (4000+RPM) seem to be increased? That would indicate that your cam is retarded, and that you would need to advance it a tooth (if my theory is true).
It is not uncommon for cams to be ground 10 degrees off or more, especially if it is a custom cam, which is why they all need to be indexed. However in a very-high production situation, I'd be surprised if your cam was ground that far off (but it is still not impossible).
bobc455, I've replaced the timing belt several times before, but at the time I didn't have the vacuum gauge hooked up so I don't know what effects it has had in the past. I've always put the timing belts on myself so I know they are are installed with the timing marks. I even tried taking the belt off and tried setting it 1 tooth off each way of correct and didn't see any significant change in vacuum, maybe 1 inch of vacuum difference. I've also tried adjusting the timing both ways at the distributor to the point it stalls and once again only about 1 inch variation. With the 1.9L engine and all of it's 88 HP it's hard to tell much difference in power either way. Really it seems like if anything it's got less power, but who knows one of the horses may have died. After all this is the Escort that has nearly 1/2 million miles on it.
RoadWarrior, this is one of the Escorts they made that didn't have a PCV valve, just the two vacuum orfices and I've been from one end to the other of those vacuum lines several times and found one that was in question so I replaced it, but didn't help anything.
I have question to ask. Suppose the MAP sensor went bad at the same time I changed the timing belt, what effect would that have on vacuum? Any? The only thing is, I would expect the fuel efficiency to have dropped more than 2-4MPG if that was the case. Any input? If it had just happened sometime when I hadn't just changed the timing belt, I wouldn't think that had something to do with it, but I've been over it several times checking for anything that I might have done wrong, unplugged or knocked off and everything seems to be right.
I think maybe I have found my vacuum problem. I pulled the codes from the ECU and found that I had a defective ignition module. I replaced it today and took the car for about a 2 mile drive. The engine vacuum was up, but the temperature was in the mid 90's too and the vacuum had been increasing with warmer temperatures. I'll be driving the car tomorrow morning early so I should find out for sure then whether that was the problem or not. Guess I should have checked the codes sooner, but I kept thinking it had something to do with the timing belt change since that is when the problem started. I sure hope this was the problem, I'm tired of only getting 40-43 MPG. I want to see those 44-48 MPG numbers again. This has pulled my average way down.