So you had the titan aero assembled, which was working fine until you upgraded the firmware. This is strange indeed.
How fast do you extract? Usually for steps calibration I go as low as 160mm/min (2.6mm/s).
Did you extruder came with bushings or bearings? While extruding do you notice any jam at all, like the extrusion slows down or something?
Since you changed the current to 1.4 and overextruded the only thing that can think of, is that there must be a high friction issue with the extruder. How did you tighten the heatsink? I had a friction issue which i managed to solve by tightening the screws from top right (the freewheel and bearings location but very gently) , right bottom, top left and left bottom. E3D last time i checked suggest the right process should be from top left, bottom left, and move on the right side which didn't work out well for me. Tried it with both bearings and bushings and there was always some tension and minor misalignment when i was following their suggested sequence.
Something else you need to consider is in case if you are using the pancake motor (slim nema motor) is that you are close to its max amp rating and you should be somewhere around 80% of this number (1.4).