I Try very hard not to start new threads but multiple searches using various terms have not found a good answer.

The thread title basically spells out the problem. I'll add a few for details.
148k, I'm the original owner, I just put 12 Quarts of Type IV fluid through the tranny a month or so ago via the pan drain, cooler lines and dip stick tube, drain 4qt add 4qt ect.... It was doing the exact same thing prior to the fluid change. The tranny fluid had never been serviced prior to that. Under normal driving conditions you dont notice to much. But at a WOT shift from 1st to 2nd it is slow/delayed/Sluggish. This does not make the vehicle undriveable but if it is a easy fix by swapping out the shift solenoids I have no problem doing it. I also fear it will get worse and damage the transmission if it is not already. Its Paid for just trying to get another 100K out of it!!

I have read various threads for other Gens where many people have swapped out their Solenoids on A340 and A340E/F trannys, but it seemed most were not shifting at all or had other shifting issues, no reverse ect. Even read where a member shimmed his accumulator spring to firm up his shifts on a 3rd Gen. I may be wrong on the last sentence, please correct me if you know for sure.

Has anyone experienced this in a 4th gen?? Granted this tranny was only used for only the 2003-04 V6s in 4th Gens.

Any Help or links to other threads would be great.

Its been a long time since I had the opportunity to be elbow deep in a transmission, the dealership typically replaces them as entire units (because apparently all that training means we're too stupid to fix them, lol )

That's the first I heard about swapping solenoids, but it shouldn't be too much of any issue as the only real difference between the two is the tail shaft housings (the 2WD have a different tailshaft than the 4WD models), but I'd have to look up part numbers to verify it.

I'm assuming your vehicle has a dipstick since you mentioned Type-IV ATF being used. At this point you'd have to find an FSM and crack open what their diagnostic chart looks like, specs, shift pressures, ect. I'm not sure the newer FSMs have that information anymore, like say the '88 4Runner FSM that not only specified in detail pressures, but speed and so on.