So the Blazer (just hit 150,000 miles WOOHOO) (1998) automatic 2 wheel drive 4x4 option has been doing somthing funky (no check engine light, no anything) no matter if the engine is hot or cold when picking up speed and shifting from 1ts to 2nd and 2nd to 3rd there is this waiver, like its slipping in and out of gear, causing a front to back rocking, once i get up to speed, lets say 50 mph the RPMS start waivering up and down a little and there is a slight rocking like its gaining and losing power almost, no stalling, no problems starting, idles well. I was thinking maybe the shifting solenoids, transfer case control module or motor, BUT I am going to start small by cleaning the mass airflow sensor, replacing the dist cap and replacing the throttle position sensor, what do you think? I also have a sneaking suspition that I didnt get the fuel lines connected at the fire walll as well as I thought I did back when I replaced my injector...if its come lose and is leaking gas could that be the cause???

the last thing I have done to my truck was replacing all of the 02 sensors because it was smellin funky, finally my light came on and said I was runnin lean....since I replaced them (about 5 months ago) that has not been an issue.

 

First off, have you checked your trans fluid level and what color is it, and does it smell burnt?

 

I checked about a week ago...level fine, smells good and does not appear an off color...i will check again

 

Almost sounds like a problem with the torque converter, like its locking and unlocking, But honestly, these trannys are not my strong suit. someone should chime in that knows more than me.

 

Lol well thanks for trying at least

 

and a failing/worn boost valave will cause the problem where your tranns is constantly upshifting and down shifting.

 

So...i did some checking yesterday, noticed my oil cap smelled like gas! Replaced the pcv and did a oil and filter change...seems to be running much better...going to wait a couple days before smelling it again...replaced air filter and found a small crack in my radiator, did a radiator plug for now, replacing it next weekend....think there is also acoolant leak near the heater core....going to have my mechanic friend help me check the Trans lines and find any other leaks next weekend...ug.