Check Engine Soon

[MrJones]

i received a code of p0171 and 172 i had the o2 sensor repaced and the code cleared, within the same day the check engine soon light came on again giving the same codes the machanic said it was a coil pack so he replaced it and a day later the light comes on again, i am running out of money, sometimes in the morning when i start the car it idles down then it shuts off after the second attempt it stays on. what could be causing this problem?

[THT]

If there was one bad coil pack, replace them all. Year of your Max?

~THT

[MrJones]

2000, where should i look to find inexpensive coil packs?

Thanks