My car seems to not want to go anywhere when i put it in drive, it slowly starts to go and then spudders and then goes into gear and runs smoothly, all gears run great....until I stop then it does it again and I usually have to drive extremely slow until it "catches" and then it runs fine again, the rpms look fine and it shifts like it should. When I put the car in reverse, it shakes and shudders then smoothes out. Ive been reading online that it sounds like the pressure solenoid is bad, should I spend the money on the part or could it be something else? Please help!