Heavy chatter in X axis on a keypad move

Im wondering if I have a issue Im not seeing a cause for. I moved my bot along the x axis today and noticed a horrible chatter in random sections along my 96" table. I say random because it would happen in different spots and not the same spots every time. I have a prs alpha 96x48, y and z axis are fine. I went through what I think is pretty standard trouble shooting steps but it seems I am not drawing any conclusions. Jog at 12 ips produced no chatter from the keypad, move at 4 ips does. MX command produces no chatter, but I had a error there: Mx8 moved perfect (although I didnt measure it looked right), mx-8 hit the stops and errored. Mx80 produced no chatter, MH produced no chatter. I took of the steppers, checked my pinion and gears, had some sludge on the back side of gear, cleaned re-lubed, no rust. Re aligned and greased pinion. Base of stepper shaft looks clean with a little dust around the edges but nothing serious or obvious. Repeated on other side with same results. Once back together I am still getting the same results. I also noticed that My gantry seems to have maybe an 1/8th inch slop in the x axis at the home position. My machine is roughly 5 years old (bought one year previous, but not set up for a year). Any ideas? I thought maybe I should replace gears just to eliminate that as an issue, but I honestly am not seeing any signs of wear, maybe a little shiny on one side of the teeth, but normal enough. I have yet to true my machine since the original assembly, should that be my next coarse of action? Am I missing anything obvious? What is weird to me is that I get no chatter in move command and none in jog from keypad, but move from keypad does produce the chatter consistently at random places along the x axis. Thank you for any help in advance. I need this machine back to 100% asap, as it is my familys bread n butter.