A flush is a waste of money,,,,,fluid & filter change a good idea,,,,the reason for a flush is to exchange fluid without disturbing filter,,,there is a risk of allowing contaminents into system when removing filter,,,then the finger pointing starts,,,,YOU SCREWED MY TRANSMISSION UP !!!!!!! when the problem was already there!!!!! the lag or delay can be caused by converter drain down from sitting over night,,,,to filter with restriction,,,could be a problem with coverter but normally they work,,,or they don't....the jolt,,,,hmmmmm.....the soft transition,,,there is a vacume modulator on front of trans,,,this sets,,,adjusts line pressure of transmission,,,looks at vacume rise and fall and adjusts accordingly,,,may want to replace this,,,whatch what you are replacing with,,,several design variations of internal valve ,,,,,must replace with same internal valve train,,,modulator may not look the same but the valve train MUST be the same that came out,,,also check hoses ,,tubing supplying vacume to modulator.......overfill transmission by at least 1 quart,,it needs it!!!!