MAF vs O2 sensors...symptoms

[realistic]

Hello, I'm a noob girly and I am trying to figure out the next thing to replace on my 2001 Corolla.

I've searched through the forum and found a few suggestions for my problem, which seems the be a common issue. The most suggested solutions are to replace/clean the MAF or to replace one of the O2 sensors. Here's the deal:

-check engine light has been on for awhile now
-the car sometimes hesitates and sputters when starting out from a stop...warm OR cold. it seems to sputter more aggressively when its been raining out.
-recently the car likes to turn over, but not start up. this happens 2-3 times a week now. usually just time passing gets it to start up, or banging on the fuel tank.
-im getting "fuel too lean" and "multiple cylinder misfire" engine codes

My boyfriend replaced the fuel pump and cleaned the filter and it did nothing. He's cleaned the MAF sensor as well, but I may get him to try again.

Are there any symptoms here that would indicate which problem it is more likely to be? I already wasted $150 replacing the fuel pump, I don't want to waste anymore money! I would take it to the dealership but I really don't have the cash for it.

[Chris Corolla S]

Did you check the plugs? Missfire is usually plugs.

[01loadedLE]

it may take several cleanings for the maf to finally work, and dont use any cleaner that has silicone in it because that confuses the sensor. if the cleanings dont work the maf sensor will cost around $130 if bought online and installed yourself. if you get new plugs which you shouldnt have to if youre under 100k miles then buy ngk or denso brand.

if your boyfriend was the one with the idea of replacing the fuel pump then get him to pay you back because it wasnt even needed. this is most likely a maf problem as many people have had similar problems with 01's including me, and usually it happens around 60k miles.

[realistic]

thanks so much!

[deekay140]

you got a bad injector, replace all 4