bucking at low RPMs then check engine light comes on if I coast in gear
I have a 1990 fox as my daily driver, it has a 3in Anderson Power Pipe, Pro-M 92mam, Explorer intake, GT 40P heads, 24Lb injectors, Lunati cam, BBK headers, Proform roller rockers, FRPP OE hydraulic roller lifters, 3.73’s, Griffin Dominator radiator, Mac X to Flow Master mufflers, and SCT 4-Bank Eliminator chip to tie it all to gather. I recently installed the 24lb injectors and the Pro-M 92mm MAM, and the Anderson Power Pipe; the car started bucking real bad at low RPMs so I sent the chip to BAMA to be re programmed for the upgrades. I was hoping that that would fix the problem but it has only gotten worse, I have checked for vacuum leaks, replaced the TPS, MAP sensor, and the sparkplugs, SP wires, and coil are new. The buck is not as bad as it was, but now the check engine light comes on if I coast in gear or down shift and if I come to a stop or put the car in neutral while the check engine light is on the RPMs will surge from 750 to1300 a few times and then the car will die. It also won’t start on the first try as it used to. What could be causing this?