In the last week my check engine light comes on and goes off. It seems that it comes on if I let up on the gas pedal. It seems to come on more regular now. I try to self ûdiagnosis by using a voltmeter but couldnÆt figure it out. So I took it to my local mechanic and he came up with code
#12 Mass air flow sensor problem and code
# 21 coolant temp signal out of range
He said that #21 was not a problem but #12 could be a big cost.

Has anyone gone thru this?
Any advice to what I should do?

1989 raider 3.0 liters
Eng 6G72
5 speed
72,300 miles
Everything is still kept stock and it seem original

Thanks ahead of time last time you were very helpful