I had a similar problem with Character walk cycles….It was Step, pause, step Pause, Set Pause. So the Key frames went like this, Position Keyframe move to different Position Keyframe hold to same Position Keyframe so on and so forth. I had every Keyframe Linear, but dumby After Effects step added Bezier Wobbling between the two same Keyframes…..I resolved it by selecting every other Keyframe and changing them (Aple Click or Right Click on Keyframes) to Hold where there should be a hold. It is ridiculous because Linear doesn’t mean linear in AE like it does in Flash.