1996 Lumina 3.1 L engine mileage 100,450

Took car to one of the car parts stores and had the codes read for the on/off again red check engine light...Codes read P0102, P0134, and P0300.

The misfires on all at times concerns me; but it could be tied to all codes read!??
Is there a tie between these codes? I have read the codes but they seem to possibibly be common causes to the same problem! Car runs good...maybe a little rought idle. Gas mileage 20.5 mpg in town. New plugs recently (all 6).

The check engine light comes on and may stay on for a while and goes off for sometime. Then again it comes on??

Any help will greatly be appreciated, before I spend a lot of $$ ..
If you have experience same--please share your findings and resolving the problem...

Many thanks in advance!

Although I'm not completly sure what those particular codes are for, I do know that the "P" prefix means it has to do with the powertrain.

p0102- Mass aiflow sensor- high frequency detected

p0134- upstream heated o2 sensor insufficient activity (bank 1, sensor 1)

p0300- cylinder misfire detected (random)

Copied from my Haynes manual.


Jim