Hello! This is my first post so I apologize if its in the wrong spot. I have a 2000 Blazer 2dr. 4.3 with a stock 4L60E trans. and 138k mi. From 0-45mph in gears 1-3 it works near fine except under heavier load (uphill) it wont change gears until 2800rpm with little "pull" during 2500-2800. However the problem occurs when I hit 50-55 into overdrive. I can cruise normally in OD without the tach going over 2k, however if I need to speed up or start moving uphill, I can press the gas pedal down considerably and only get a little "pull" with the tach still stuck around 2k. I then press the pedal even harder, it switches to third, the tach jumps to 3-3200k, and the truck surges or "jumps" torque like its stalling out. It then downshifts normally if I floor it out of 3rd or slow to a stop. Very rarely it will do this surge in 1st gear as well but not nearly as bad.
Ok as far as troubleshooting: The battery and alternator are brand new. I cleaned my MAF sensor, the throttle body, and my EGR valve (which did WONDERS for my power), all in good condition. I had the trans. fluid and filter changed and the trans. shop said nothing was in the pan and the comp. read that I have all gears working. My oil, filter, and air filter all new. SO......... my next guesses are...... TCC solenoid, VSS, and TPS from what research has shown me. Anyone have any ideas or the same problem? My other question is if I replace the TCC solenoid, is it wiser to just replace them all while the pan is dropped to save time in the shop down the line? Thank you for your time