Intermittent SES / fuel trim codes

[rmr2122]

Hi guys,

I have an '06 3.0 with 100k. Recently did a major engine service--OFHG, Vanos, coolant pipes and hoses, water pump, thermostat, and installed the GAS CCV replacement kit. I've driven around 3k miles since I completed this project without any issues. Around 200 miles ago, I also replaced the O2 sensors and MAF preventively (no codes). I used a VDO MAF and Bosch O2 sensors.

Two days ago I had an SES pop up with E3/E4 Fuel Trim bank 1 and 2 permissible range exceeded, as well as cylinder misfires on 1, 4, 5, and 6.

I cleared the codes and the light didn't come back on until my drive to work today. Today, only the E3/E4 Fuel Trim bank 1 and 2 permissible range exceeded codes popped up.

What could cause these codes? Could I possibly have a vacuum leak causing these codes? I didn't smoke test the engine after my big project, but again I've driven about 3000 miles since then and haven't had any problems.

I have the Foxwell NT510 scan tool, but I've never used it to read live data/fuel trims before.