1999 blazer transmission problem??
 

I have a 99 chevy blazer LT 4 wheel drive 4.3L and 460le transmission. My problem is the speedometer does not work causing the transmission To not shift out of first gear when in drive. I can manually shift into 1st gear and into 2nd gear but when I manually shift to 3rd it acts as if it is in neutral and the engine just refs with no movement of the car. I have already replaced the vss and the 3-2 solenoid and both shift solenoids yesterday. When I went and added back 4 quarts of fluid after putting together the underneath of the truck again I checked it and it was low. So this morning I took it out in low 2 gear to the auto store and got more fluid, got home cycled through all gears and checked the fluid and it was extremely high so I syphined some out and brought it to just about the line for cold so it was now a little low, I took it for a drive and it was working perfectly normal shifting and the speedo was working, got back home and added just a little more fluid to bring it up to normal and drove it again and it worked fine, I then let it sit for about a half hour or hour then it did not work again and I'm back at square one with no speedo or shifting.I'm running out of solutions and money and really have been avoiding a mechanic. Any input towards this problem would be greatly appreciated thank you.