99 Lariat 4x4,5.4 when accelerating from a stop tranny slow shifting between 1 & 2 nd gear,when it does shift goes in harder than normal.If I accelerate fast from full stop shifting ok.If I shift manually between 1 & 2nd ok.No flashing from O/D light.There is 135.000 km on truck.Planning to change oil and filter tomarrow.Fluid color looks ok and no burnt smell.

 

Good start, mine acted up kinda the same and new juice seemed to solve it. Is this it's first fluid change? Otherwise, it may be this little spring or something above the filter, some piston or something but I hear easy to fix, hard to diagnose.

 

See also this: https://www.f150online.com/forums/sh...d.php?t=290525

 

I left out that I also tow a fithwheel trailer and after talking to a mechanic today,he explained that the shiftting may be different due to my recent towing of the trailer.Apparently the computer can alter the shift pattern when towing?I am having him due the fluid & filter change ($150 cdn) my cost for oil and filter $100 cdn.So I hope thats it he will let me know tomarrow.

 

get a "factory tech" or "transgo" shift kit