Howdy everyone. First off, I apologize for the lengthy post. I have a problem with my '00 blazer, while I am accelerating it kind of "surges" I guess you could say. Right around 2100 rpms, the rpm needle will drop about 50-100 rpms and hang there for 1-2 seconds then advance back to 2100 and continue to accelerate normally. Does this in every gear. It doesnt feel like there is a missfire, idles smooth as well. The accelerating is a little sluggish I think, but that could just be me because my previous vehicle had a v8. In addition to THAT problem, when I'm cruising at any speed above 55, if I hit the gas enough to get it to downshift to 3rd, the rpms will jump from around 1900 to 2100 and stay (without gear change. I believe this is normal torque converter unlock?) BUT, it will jump again (very slowly this time) to about 2300 rpms and then it will grab 3rd. It feels like the torque converter unlocks twice before downshifting! (basically every downshift to 3rd goes like this. OD at 1800rpm, then t.c. unlock, then a sluggish rise in rpms until it grabs third.) tranny fluid is good and at correct levels, completed a basic tune-up (plugs, wires, distributor cap & rotor, cleaned maf sensor also) No lights are on except for the abs light, and thats because i pulled the fuse. (abs engaged without brakes applied) Any thoughts? Thanks in advance!

 

I read a previous post on here that was similar to your situation. It turned out to be a bad tach. However I would check into the throttle position sensor as well. Hope that helps!

 

Hopefully Its just the tps, i'll check into that tomorrow. Thanks!