OK, let me give the long story so, hopefully, the accurate troubleshooting can happen faster. Have lurked the board for a while but was always able to work my way through problems with other cars without the need to register/post.

1. Purchased the car with a lack of power and an engine light on. I check the codes and it showed MAF performance. Datalogged and checked freeze frame data and both showed the sensor was junk. Purchased a new MAF and installed. All was well and the car drove great, got great gas mileage (30+ on hwy).

2. Car sat for about 2 or 3 weeks (after putting a couple thousand miles on it). Started the car to take on about a 200 mile trip and it seemed to have an extended start time. Car started after 5 seconds or so. Drove to the end of my street and the CEL came on. Checked codes and it was a single cylinder misfire. Drove back home and parked it. Checked ignition coil and it was defective. Put new ignition coil on along with new spark plugs. Car now ran smooth but seemed to have a "stepped" boost application instead of just hitting boost nice and hard.

3. Unhooked battery and followed the relearn procedure to a T. Unhooked battery terminals and touched them together for about 5 seconds. As insurance, I also tapped brake pedal and turned key to the crank position. Let sit for 5 minutes or so then hooked battery up with key in the on position until airbag light turned off. Turned off key then turned key on and started car. Allowed to reach operating temperature then placed in N for 1 minute. Put car into D for one minute then drove the car between 20 and 50% throttle until it was in top gear. Drove on the highway at light throttle after that for approximately 10-15 miles. Came to stop, turned off car. Idle was slightly improved but the stumble/stepped boost feeling was still there.

4. Put old spark plugs back in and put another new MAF on the other night. Performed relearn again. Found that when the car was filled up, it got a bad batch of fuel. Started car and used my fuel pressure gauge to drain the tank. While draining the tank, I noticed a TON of tiny air bubbles in the discharge hose. Placing the end of the hose at the bottom of the container produced bubbles similar to what you would get by lightly blowing through a straw into water. I am 99.9% sure that this is what is causing my hesitation. Obviously, injecting air will not yield a very good combustion/burn process...

My question is, no engine light and air bubbles in the fuel would be what? I suspect that somehow air is either being introduced into the system inside the fuel tank (suction side of pump, is it a plastic body???) or, if regulator is in tank, could it somehow be letting air come in there? Other option would be a fuel line too close to the exhaust somewhere and it is boiling the fuel.

Any ideas? Anyone have this situation before?

 

Wanted to update the thread. Intermittent missing/surging was caused by defective coil(s). Went ahead and put all new coils on tonight and the car is now smooth as silk. Went into boost a few times on a 30 mile drive then just cruised on the highway. Averaged 28.4 mpg for the drive. Planning on doing another reset tomorrow since everything now appears to be totally inline again. New plugs will go back in before the reset, too.