depends, some cars if the idiot light comes on the computer goes into some default setting that typically isnt the best, some ignore that sensor and adjust according to other sensors.

but all in all prolly best to fix it. as if it really goes out it can cause loads of weird issues

also check your vacuum lines, if tier cracked or leave black marks on your hand replace them ALL. thier dry rotting and most likely leaking

filled up today and i dipped below 40mpg. aside from a few extra city miles, nothing noteworthy except the check engine light. in fact, prolly warmer temps than the last few tanks.

maybe that MAF sensor does need replacing. there are no detectable vacuum leaks.

On my 92 Nissan, my injectors fail about every 4-5 years (1 year warranty on replacements). When I notice a rough idle (but not yet a regular miss) and a little lack of power on the interstate I get out my digital multimeter and unplug all 4 injectors and check the resistance between the contacts. I'll spot one with 3 times the resistance values as the rest and I'll replace it and all will be well for a year or so until the next one gives out...

I assume the bad injector doesn't inject as much fuel as it should and thus the oxygen sensor likely sees a lean condition. I have OBD0 so I don't get a CEL or code.

Comparing the resistance of the injectors shouldn't take but 5 minutes and would eliminate an electrical failure in one of them (but would tell you nothing about if one was clogged).