I have a ‘99 Blazer ZR2 and I’ve been having some issues with it shifting through 1st gear. It shifts fast and smooth as it should but it shifts late, like it won’t shift until it’s past 3 grand. I did just replace the shift solenoids and filter (drain and fill on the fluid, didn’t completely flush). Is this something I can just fix by rebuilding the valve body or is this a whole trans rebuild or new trans replacement?