w123 transmission shifting

[Curkey]

I recently bought a 1980 280E and am having some transmission issues. I have hardly any acceleration when coming from a stop. When I merge into traffic I have to wait for a large opening. When on the hwy I can accelerate without too much trouble but then I notice it shifts rather hard. From the searches I have done on this forum it seems like it might be vacuum related. I found a DIY for adjusting it but it is for a diesel car. Is it the same? The VIN on my car is 12303312070741 if that helps. If I am leaving anything out please let me know. Thanks in advance for any replies.