Can't rev over 2500-3000rpm max

[Lofgren__]

First of all hello! Im new to this forum but I've read some useful tips about my problem but the thread owner stopped posting about it.

I just changed IP on my 945 tdic, since the last one stopped delivering diesel. The new pump worked very well After I changed the rear "seal" on the shaft. Also changed the o-ring on the "accelerator pin" it worked after that too so I drove it for 1 day to work. Then I started it to drive home, and then it didn't rev past 3000rpm max! But it started instantly. I got all the way home. Then I filled the pump with ATF oil and let it sit for 2 whole days. I started it and it ran fine just as before. Drove it to work and now the problem is back...

What should I do?
Planing to change the on/off thingy (magnet ventil on swedish)

Sorry for my possibly janky English and lack of vocabulary.