When I took my car to Advanced Auto and explained that the car is not driving smooth, like I am trying to push it too hard, too fast, going from 20 to 30, roughly, and then 30-50 roughly; and then when I enter the interstate, it doesn't really transition well, without feeling like I am pushing it too hard, too fast, when I try to go to 55 or 60, and it takes time to get to 70. Today the RPMS when I was at 70 = 3000, and as I took my foot off the accelerator, to bring it down a little (e.g. decreasing from 70 to 65, and then 60), the rpms decreased proportionately back closer towards 2000 rpms. I also have had my check engine light on for a month, with a P0401 code, even though the car had been running well, a month ago.

 

is the tachometer bouncing around ? if it is, replace the ignition coil, clear the codes, see if it comes back, we'll worry about the p0401 later