Similar problem for 1997 Ranger with 4cycl, automatic . . . Often "pauses" shifting from first to second . . . It shifts eventually. This happens for only about the first 10 minutes after starting a cold engine . . . Afterward the problem doesn't occur. When the pause happens, manually shift to second always makes it go into second immediately . . . I then put it back in drive. Starting off with gear lever in first and manually shifting to second always works. Fluid looks good . . . Is red and clear . . . It is slightly low but definitely within the hatch marked "filled" section. The dip stick has printed on it words to the effect "do not add fluid unless below hatch marks" so I haven't added any fluid. Otherwise, the transmission shifts smoothly through all gears.
Ill assume this is an automatic transmission. The very first and obvious thing to check is the transmission fluid level. When the engine and transmission are up to normal operating temperature, park the truck and turn off the engine. Check the transmission dip stick and note the fluid level and condition. Low fluid can be the cause of slipping. Normal level but with Foamy or milky appearing fluid can be a sign of internal problems and result in slipping. Very dark, brown or black fluid (even a burnt smell) can be a sign of warn internal friction plates which cold lead to slipping.Is there anything else besides the slipping while starting out you have noticed? Can you describe the feeling and or sounds you hear before, during and after the slipping? Is there any condition, or period of time when driving when you do not notice this or changes the slipping in any way, for better or worse? One thing you might want to try right away is to see if manually putting the gear selector into the lowest range, which is presumably "1" or manual first gear. Does this affect or change the slipping in any way?Some other helpful factor to diagnose this would be how many miles are on the transmission? Has any mechanical work been done to it? How is the truck driven (mostly driven softly, aggressively, city, highway)? Has the transmission fluid been changed regularly or in compliance with the trucks recommended service schedule? Is the truck stock, or has its engine, drive line oe suspension been changed in any way? What does the fluid on the transmission dipstick look like