Recently purchased a 2007 Toyota Tundra with a 4.7L engine and the A750F 5 speed trans w/152K miles. Purchased about 5 months ago. When it is cool and even worse when cold (the colder it is the more likely it seems to occur) sometimes when I first take out for the day it does not want to shift out of first. I usually have to back off the throttle a bit even though not accelerating quickly at all to get it to shift. Currently now that it is hot outside this rarely occurs. I was thinking of doing a fluid spill and fill then a pan drop, replace filter, and fill with new fluid to see if it will help however I will not likely know until it starts getting cooler if this corrects the problem. I do not think the fluid has ever been changed from talking with the previous owner. He seemed very meticulous with maintenance except for the trans. I also noticed Trans Go and Sonnax both make shift kits (links below) that both claim corrects common issues with the A750 (and some other models) transmissions.
Thoughts on if the fluid and filter plan has likelihood of success in correcting the issue I described above or if one of those kits likely a good investment. The transgo kit is a little cheaper however includes a drill bit so drilling something required which makes me a little nervous although I would have a shop install it. The Sonnax does not have the drill bit (and I do not think requires any drilling) however although a little more expnsive seems to have more parts included in the kit. I like the truck and plan to keep it long term.
Transgo
Sonnax
Thoughts on if the fluid and filter plan has likelihood of success in correcting the issue I described above or if one of those kits likely a good investment. The transgo kit is a little cheaper however includes a drill bit so drilling something required which makes me a little nervous although I would have a shop install it. The Sonnax does not have the drill bit (and I do not think requires any drilling) however although a little more expnsive seems to have more parts included in the kit. I like the truck and plan to keep it long term.
Transgo
Sonnax