Have slow leak of coolant. Have changed radiator & cap and pressure tested to ensure no leak. Still have coolant loss. What else might it be

If your water pump is going bad it will leak out of a small hole designed to relive pressure and signify a bad water pump. Grab your water pump pulley (that year should have a diagram over top the radiator to show belt coarse and pulley position and u can find it in a repair book or normally a parts store can help also) with the belt on try to wiggle it. If it moves side to side or wobbles you have a bad water pump and it need a to be replaced or rebuilt if it's not in too bad of shape depending how long it's been bad.