This will be long and probably ramble on but it's driving me nuts.
2005 Pontiac Vibe base model. 180, XXX miles. This has all been happening since Saturday.
We've been getting a really rough idle at stop lights which drops the RPM's really low but never stalls. Putting it in neutral cleared it up we could take off and go with no check engine light. Now, it has progressed to happening randomly throughout the day sometimes it clears up sometimes it continues as we take off and clear around 3,000 RPM but is accompanied by a flashing CEL for cylinder 1 misfire P0301. At one point it also threw a bank 1 lean P0171 but only once and hasn't come back. The P0301 is occurring quite a bit but it is random.
For instance, sometimes I can drive it into town without any missing or codes, other times it acts up for a bit then clears up and then another time it misses like crazy and throws the flashing CEL for the P0301.
Things I have done already:
1. Chevron in the tank
2. Changed plugs (Autolite iridium)
3. New coil (also swapped around and the code did not follow)
4. New Air filter
5. Cleaned and then replaced MAF sensor
6. Checked for vacuum leaks but I couldn't find any
Went for a ride today after changing the MAf and it ran good for 15 minutes then started acting up. Got home, restarted it still rough. Rinse and repeat and it cleared up on like the 3rd restart but if you gas it fast there's a quick hesitation before it revs.
From all of the reading I've done the last couple of days from mostly here other things it could be are:
A. Intake Manifold Gasket (wouldn't this be more consistent and heat dependant?)
B. Fuel Injector (My gut is now saying this)
C. IAC (didn't clean this because I cannot get the gasket and o-ring locally and it scares me to reuse the rubber gasket because the coolant lines)
D. Fuel Pump
E. O2 sensor. I've read this is very unlikely
Any thoughts? I'm ready to toss in the towel.+