93 ZJ 46RH Transmission Questions

My biggest problem with transmissions is being able to diagnose transmission problems by looking at the RPM. I've never took the time to study shift times by the RPM. I've been watching mine here lately and from first to second to third, it shifts at 2500 rpm with the OD light on. Is that about right for a healthy transmission ? I'm asking because in the morning when I started up and drive, it drives as if it's congested and I have to speed up to 40 miles an hour for 5 to 10 seconds for it to clear up and sound like it's running right and shift fine because during the "sluggish" stage, the transmission seems to prolong shifting. And this is after I've warmed up the engine.

 

I know we talked about this light before but I don't have a clear understanding as to what it actually does, how it affects the transmission positively and negatively, and what exactly it causes the transmission to do positively and negatively. I just want a clear understanding so that way I don't have to keep asking the same questions. Like I said before in the beginning, I worked on cars most of my life because my grandpa and uncles are mechanics but I've only been given the simple answer as to what parts play a role, as I pull and replace them for him.

 

I know it probably sounds silly but I honestly don't know...how do I know when I'm in first gear, second gear, third gear, and fourth gear ?
When it's in drive is that first gear?... and when I feel it shift, is that second gear and ongoing? (First shift is second gear, second shift is third gear, third shift is fourth gear ?) What are the speed rates for each gear? First gear is 0 to 25 miles an hour and so on... Or is it different than shifting every 25 miles an hour?

 

Like just now coming back from lunch, the sluggish run didn't stop and was very hesitant about shifting into second gear. It did not shift into 3rd gear and my RPMs were going past 3000 before I let off the gas pedal. The OD light was on

 

If you're referring to the O/D OFF button, thats turning the over-drive gear on or off. When OD is enabled rpms are lower for highway speeds resulting in more efficiency.

 

When OD is off the trans will be in a 1:1 gear for better passing power or to handle tow loads