2001 4cyl AT shift problem problem

I am new and have a 2001 4 cyl SR5 Xtra Cab with AT, 205k miles.. Just recently the trans started acting strange. If I take off gently from a standing start it will shift from 1st to second, no problem, shifting somewhere between 1000-2000 engine rpm. However, if I maintain a constant pressure on the accelerator it will go up to 3200-3400 rpm before shifting into second. I have changed the AT fluid and filter twice in the past 2 weeks, checked the valve body for any obvious damage, no large metal flakes, removed the EFI fuse for 10 seconds that somebody suggested, have checked the resistance on the TPS, was in spec; all to no avail. No engine trouble light either. I have an Alldata subscription and am using that to troubleshoot. About all that is left is to check is the vehicle speed sensor, and then the governor valve. If it's not one of those last two things, i don't know what else to do short of replacing the transmission. Does anybody else have any other ideas? thank you.

 

When I look at and disassemble the governor valve and/or the vehicle speed sensor, what do I need to be looking for that might indicate one or the other is the problem? Do I clean the governor valve and the VSS or do I just need to replace one or both? Or is there something else I should do? Thank you. -Craig

 

None. Once it shifts into 2nd and beyond, there are no problems. I routinely commute an hour to work on the interstate and stay at 70 mph. O/D works fine, etc. -Craig