I have a 99 GS4 with 136k on the original mass air flow sensor. I changed my o2 sensors even though there was no code and noticed a huge difference in how responsive the car is. The car is 21 years old I figured they were not 100% anyway. Does this same logic apply to the MAF? It’s over 20 years old is it either it fully works or it doesn’t? Or is this a part that will still work but not as good when it’s 20 years old. I know like a door lock it either works or it doesn’t but the sensors are different. Do you think I would notice anything changing it? Also does anyone know about the gasket. I am reading online the gs400 MAF doesn’t come with a gasket?

 

I'd think you'd be better off just cleaning it. Get some MAF sensor cleaner and take it out, spray the inside down and everything. Trust me, it makes a difference. When I cleaned mine, a whole bunch of dust came out (probably because the filter was partially ripped). Try it and see if it does anything.

Also, from what I remember all 2GS MAFs come with gaskets.