I just changed out intake gaskets on my blazer (4.3L) and now it runs great for the most part. If I am on a grade and the engine is under load though, say at 55MPH and the load it takes to maintain speed going up a slight hill, there's a periodic shudder, like about every 15 seconds that lasts about a second. It seems like the thing is in between deciding to downshift and then deciding to not downshift.
This didn't happen before I changed the intake gaskets, and I am wondering if any of you might have a suggestion as to what I might need to check. I almost wonder if there might be some sensor or other that might cause that sort of behavior.
Any help would be GREATLY appreciated...
Carlton