Occasional miss going to third Gear
 

Have a 99 Blazer with the 4L60E Auto trans. Initially had a "SES" light on and it took alot of RPM to get rolling from a stop. Also didn't have 4th, stayed stuck in 3rd. Coded to a 758 which was the 2-3 shift solonoid. Took it to a trany shop and the guy said he swapped out the B solonoid and changed the fluid. So now the lights out, take off from a dead stop is good and it acts like it's in 1st when you take off like it should be but there is an occasional slip/miss going from 2nd to 3rd. RPM seems to climb to about 21-2200 when it shifts normally, but it will occasionally go to 25-3000 RPM and when you let off the gas rpms drop and it drops into 3rd. Seems to happen more so when its been running for a while, good and hot. Anybody have any ideas? The 2-3 SS did solve some of the problem but not quite all. Any suggestions would be appreciated. Thanks.