native.irishman

I recently purchased a used Remington 700 and I took it out today to shoot it for the first time since buying it and  the accuracy was atrocious. I tried firing 3 round groups and the shots were all over the paper. Some didnt even touch the paper. My rifle sits in a choate custom stock, has a timney 510 trigger and for the optic I use a vortex crossfire ii 6-18x44 scope. The ammo I was using was some 150 grain reloads I picked up at a gun show. They're copper plated flat nosed rounds. I was shooting at 100 yards. I wasn't expecting sub-moa accuracy or anything but I couldn't get 2 consecutive rounds withing 6 inches of each other. The rifling in my barrel isn't weak or burnt up or anything. So what am I doing wrong?

When I'm driving if I push the gas too hard my car starts to shake. It feels like its shaking side to side if that makes any sense. The first time this happened the check engine light came on and when I got it checked it read bad O2 sensor. I got it fixed and I still can't push the gas very far down before it starts to shake. I can accelerate slowly all I want and its fine. What could that be? Another thing it does is from time to time (maybe once every 1000 miles or so) it will jerk and slow down for about 1-2 seconds when it goes from high 30mph-low 40 MPH. Its really subtle and my passengers dont usually notice it but I do and it freaks me out. I'm going to get a new fuel filter soon. Would that help?