'91 535i running great, but hitting rev limiter at 5500 RPM?

[paanta]

All,

My new-to-me 535i seems to be hitting the rev limiter at 5500 RPM. It pulls very hard from 3K-5K, then tapers off fairly quickly and hits a hard limit at 5500 RPM. I've not tried actually holding the car there and trying to drive past it, but I know what a rev limiter feels like.

So...
A) The tach is off by almost a thousand RPM. I've got an indicated ~85mph when it hits the limiter at 5500 rpm in 3rd. Is that the normal road speed you'd expect at that engine speed?

OR

B) The chip/dme is wacked out. It's got a Mark D'Sylva chip in it from the previous owner. Maybe it's bad?

OR

C) There's some sort of fuel problem that is happening consistently and abruptly at 5500 rpm, given the impression of a rev limiter. That doesn't seem the case, since the car is really strong and running fine otherwise.

Not being super familiar with the fuel injection in these cars (though I have lots of experience with the E28 + VW/Audis) I don't know if there's some common avenue for this sort of freak out.

It really almost feels like the tach is off. The whole power band seems shifted a thousand rpm compared to the feel of my e28 535is w/ Jim Conforti chip which is still accelerating pretty hard at 5500 or 6000 rpm.

Anyone have this happen before?