1st gear pulls to 7000, 2nd gear only pulls to 6200, 3rd gear barely makes it to 6000

[x88]

Hey guys. I searched and couldn't find anything that was helpful for my situation.

TL;DR: Car doesn't want to rev past 6k under load.

My current setup is a 1987 325i swapped with:

M52B28 with OBD1 electronics
5 Series 3.5 inch MAF
21 LB pink injectors
413 DME with Miller WAR chip
Supersprint knockoff headers with custom 3" exhaust, magnaflow high flow cat
Vibrant resonator and turbo muffler.

I was told the PO loaded up one of the stock WAR tunes, my guess is the "M52 OBD1 Manifold 21 Lb Inj 3-5 MAF.mpc" (at least I hope)

My problem:
I have a weird issue where first revs out through 7000 rpms fine, but only about 6250 in second, and only 6000 ish in third.

If I hold it out to 6500 ish in second it’ll let me....slowly. From 6250 to 6500 it will take a while, still full throttle, and then right as I shift into third it hesitates real quick like as if I let off the throttle, which I’m not (I’m on it as soon as I'm in gear), and then it goes fine.

If I shift into third at 6000 ish , it doesn’t do that. Gets into third just fine.

Similarly, trying to rev past 6000 in 3rd takes forever. It climbs to 6000 very nicely, pulling great, then let's off but not fully. If I stay on the throttle, it'll slowly creep past 6000, roughly 200 rpm per second, vs 4500-6000 which would take the same 1 second. IOW 4500-6000 takes 1s, 6000-6200 1s, 6200-6400 1s or more etc

Seems if I just shift at 6k there's no issue. The gauge might be reading high because it claims to be idling at 1200 and sure doesn't sound like it.

If I am in neutral, I can rev it out past 6k no problem.

I’m thinking maybe fuel pump can’t keep up?

Is there any harm in driving as is and just continuing to shift early?

I'm not really noticing any other issues.

[Caperix]

What intake manifold is on the car? The m52 manifold may be limiting your power after 6000 rpm. What is the rev limiter set at? Some of the dme's have different rev limits for different gears by using the speed sensor, is the speed sensor wired to the dme?

[x88]

Hey so looking at another post:
"Is your speed sensor hooked up or present but damaged? There is a rev limiter at 6K when there is a problem with the speed sensor. That definitely looks like what's happening there and is not related to the last break point being 6400.

After 6400 the ECU extrapolates data, just like there isn't a break point for EVERY SINGLE RPM during WOT it manages pretty well to 6.8 7K without much change in the scaling."

It's probably my speed sensor.

http://forums.millerperformancecars.com/index.php?topic=282.0

Going to try that and see.