GM-GMC: Chevrolet silverado 1500, chevy silverado z71, fuel pressure regulator

Question
Hello, my truck is 99 chevy silverado z71 1500 ext cab with 15600 miles and recently I have noticed at low rpm around 1500 rpm to 2000 rpm, in overdive and drive, it acts like the transmission is slipping or like a jerking. When u run rpm up any higher I don't feel that jerking, just at low rpm's. I have changed trans. filter and fluid thinking  that had something to do with It but still the same. Now I'm thinking it may not be a trans problem because when its in park and idleing I Hear a miss or a shutter, I have also changed fuel filter and plugs/wires in the last 15000 miles.  Also 7 out 10 times on a start up it won't crank one first try, this has happened even with the last owner, which he told me and replaced fuel filter and plugs thinkin it mite fix. Thanks,kh

Answer
unplug the map sensor and see if it still has that same shutter if it does not i would recommend replacing the map sensor.

low fuel pressure will also cause this issue, knock sensors will cause a slight shutter, fuel pressure regulator maybe an issue.

i would try the map sensor trick first though unplug it .