1. Sounds like the torque converting locking and unlocking, it's trying to figure out if it wants to stay locked in 4th or downshift to 3rd, it also depend on what speed you are at. Sometimes you can just let off the gas and get back on it and it might go away.

2. Is the common crank sensor, someday it will just get worse and leave up a creek without a paddle. You should get that sensor replaced soon.