I looked up the sending unit choices online (just match the number of ports and the side it is on), and then searched locally for the same item. I don't think there is any big difference between brands. I recently replaced both sending units in my truck when I cleaned the gas tanks, and I don't have any problem with slosh causing a change in reading.
I recommend also switching to rubber fuel hose that meets SAE J30R9 (high pressure) or SAE J30R7 (low pressure) standards. This is sold as fuel injection hose, but the key feature is that it holds up much better to the ethanol used in modern gasoline. I also used fuel injection clamps, which have full circle clamping without cutting into the hose.
My first guess for you would be a bad fuel pump or a clogged filter that is affecting flow. You might also have a float level set too low, but that is usually more evident during higher throttle.
Bruce