I have my 1996 suburban 6.5TD for more than 2 years now. I found out that my vacuum solenoid was broken. So I drove without turbo support for 2 years. I got it delivered (I'm living in Europa so it takes some time) and replaced it.

What a big difference, the turbo is working perfectly and the suburban is much more powerful.
But now I have a new problem. After the replacement, the automatic transition is shifting very hard.
Can it be caused by changing the solenoid of the turbo? Or is it a coincidence?
It does use al gears but it shifts hard in all gears. Hot or cold.
Can someone give me a starting point where to look first? (I think I have 4l80e transmission?)<!-- google_ad_section_end -->