Car loses engine power?

I noticed this quite a while ago but I never thought anything of it until just recently.

When accelerating, if I am in second gear by the time I hit 35 mph (which is almost always unless I am really trying to move), I get a non-responsive feel from the engine. I try to keep the car around 2,000-2,500 rpm's if I am driving normally (highway entrance ramp acceleration varies). I get a lot of pull and quite a bit of response (sound) from the engine before and after this dip in power. Once I reach 35 mph, I get neither of these. The sound is noticeably quieter and I typically have to rev it up to 3,000 to get any sort of capable movement through the 35-45 mph range. If I don't increase the revs, it takes upwards of five to eight seconds for it to reach 45, but if I do increase the revs, it only takes a couple seconds to reach 45. While at 3,000 rpm's, once I hit 45 mph the power is immediately re-applied to the engine, jerking the car, and anything inside the car, backwards due to the immediate power increase.

I don't have any check engine lights being thrown at all, if this helps.

Interstate driving/entrance ramp is perfectly fine. I have to accelerate harder, typically around 3,000 to 3,500 rpm's, and it doesn't have the dip in power at all. Its just in that 1,500 to 2,0500 rpm range, in second gear, and in between 35-45 mph. If I can think of anything else to help make this easier on yall I will add it

If anyone can help me with this issue id be extremely appreciative.

I noticed my transmission is slipping also which is just another thing. Im hoping it doesnt have anything to do with this. Could it be possible im skipping 2nd and going into 3rd, god help me if 4th?

I don't know why this is happening but any help would be amazing.