Solved my E34 surging problem...

[onZedge]

...it was loose bolts, all of them, holding the CPS in place. Getting to the pivot bolt behing the trigger wheel was a bitch. I had to unbolt the A/C compressor to get enough room - also a bitch.

And all I had to do is search this forum for which things to check!

[Denton]

So what was the surging like?

Mine surges too. Partial, steady throttle at a steady speed. 200 RPM variation...surges.

[NovceGuru]

My surging was fixed with a new 02 sensor. Don't be a fool though and pay $90 like I did.

[onZedge]

It recently started to surge badly going up a ~15% grade at 40-50 MPH. It always did it on the highway as well, but only noticeable enough to be annoying.

Since the latter is typically a symptom of a failing O2 sensor, I replaced that first. (According to the records, it had never been changed)

That wasn't it.

I then tested the TPS and found the part throttle contact to be intermittant. It just sat there on my workbench, connected to an ohmmeter, fluctuating. I replaced that next. (According to the records, it had never been changed)

That wasn't it.

So I searched this website for "surging". The gap appeared to be within spec but when I checked the bolts, all three were loose.

THAT was it.

I don't feel I've wasted any money replacing the O2 & TPS sensors because they were both bad, and I was doing a major tune-up anyway.