Gents,
I have been having trouble lately where if I drive the Blazer for longer drives (15-20 miles) and I come to a stop sign/light, when I go to accelerate from the stop, it won't "engage" and I can just rev the RPM's really high without moving.

I have to move the gear selector to the "3" "2" or "1" to get it to go.

When the car is "cold" or on short trips, it runs and shifts perfectly.

In some short research, I've been reading stuff about transmission "solenoids", but really not sure where they're located, how they're replaced, or if they might be my problem.

I haven't found any DIY on this site for these yet, but if anyone has any information on my transmission type or what might be the problem, it's greatly appreciated.

I have a '98 4dr 2 wheel drive automatic.

These are the solenoids I found: 4L60E 4L65E SHIFT SOLENOID 2-PACK A+B NEW AC DELCO | eBay

 

Shift solenoids do go out over time and this could be your problem. I think theyre commonly found on auto trannys. I had an old honda that had some tranny problems and there was a diy on how to clean them out. Idk if you can with these or not but definetly worth checking into instead of buying new.