hey, i have a question for you guys here.
firstly, background stats: 2001 Chevy blazer LT, 4 door, 4.3L Vortec.
Transmission recently replaced 6 months ago.

So, i've been having some issues last summer, which havent been showing over the winter so far except for 2 times. Here's what's happened:

I'll be driving along, and usually if i did a fast acceleration, such as when i turn onto the highway, or when i have been doing a lot of stop and go in rush hour traffic that's barely moving, and suddenly the truck with start acting like it can't shift up into a higher gear? it'll rev really high just to keep its speed up, and i can tell the transmission and engine is struggling. If i leave the truck turned off for a few hours, the problem goes away and it acts normal again.

a mechanic i frequent keeps insisting its the Mass Air Flow sensor, but won't actually do a check to see if that's it or not, because i have a Spectre brand Cold Air Intake system installed. the filter on it is brand new, just replaced it maybe 4 months ago. the one time this issue showed up this winter was after i replaced the filter and got stuck in a 2 hour rush hour traffic, barely going over 20kph. but since then, it hasn't happened.

im wondering if anyone else ever had this problem, and if it was the M.A.S. causing your problem. i'm debating replacing it anyways because it's an original part, and i've had to replace a few parts under the hood due to age and wear anyhow. i know i can do the fix myself, as i've removed it and cleaned it a few times when this issue's happened and had the problem go away within a couple minutes, which makes me think it probably is the sensor. I just don't want to give him the gratitude of being able to say "i told you so!" by letting him do the fix.