Hard starting, with occasional stumble and stall while driving?

I'm pretty sure there are no vacuum leaks. My new smoke machine blows pretty good, and I didn't see a wisp of smoke anywhere, except eventually out the front intake by the radiator.

If there was an exhaust leak, what kind of readings would I get from the rear O2 sensor? I can't remember, but I'm pretty sure I had a steady reading on the rear O2 sensors, and bouncing pretty good between.2 and.9 volts for the pre-cat sensors , which I believe is acting normally.

And as for the MAF, what should my readings be at idle, 1500 and 2500 rpm? And I'm not sure if my scanner reads pounds or metric.

I'd like to verify if the MAF is functioning properly, before replacing.

And lastly, any ideas on what I need to check fuel pressure. Seeing there's no Schrader valve on this system, I'm not sure what I need to be able to disconnect the fuel going to the rail, and hook up to my pressure gauge.

Thanks again for any and all help.

Thanks, I'll check those numbers tomorrow.

Okay, so the numbers for the MAF look good, and I cleaned the throttle body when I had the intake off a few weeks back.

Now the O2 sensor readings are way off.

Both downstream sensors are flat at about.01v

B1S1 is staying steady around.45
B2S1 fluctuating between.75 - 1.1

STFT B1 pegged at 25
STFT B2 fluctuates 0 - 25

Varied RPMs from about 700 to almost 3,000.

I'm lost, any help making sense of these numbers would be greatly appreciated.

I have not noticed an exhaust leak, but I'll give that a closer examination next time. Would I be looking more for it pre cat or post?

The engine revs up just fine. But stumbles heavily at idle, often stalling out when slowing down, also is very difficult to start

The special adapter needed to attach to the fuel rail is difficult to find, trying to figure out a way around that with what I have.

If it were the fuel pump, wouldn't it be starved for fuel as the RPM increases?

It seems to run fine as long as you're giving it gas, only stumbles at idle.

I would think it would stumble more as fuel demand increased, but it seems to run strong once you get it past 1000RPM

Multiple misfires code p0300.

Plugs are new, after replacing, it seems that's where the trouble started.

Found several vacuum leaks and repaired.

Have not checked fuel pressure, or spray pattern on injectors, but have gone through most every other possibility.

Pretty sure they're either NGK or Denso iridium, I always try to use an OE plug.

And always iridium when the intake manifold has to be removed to get to the back three.

Next time I'll pull the front three plugs and have a look.

These are the plugs I put in a few hundred miles ago
I removed the three in the front, and two had this burnt ring at the bottom of the porcelain. What is that telling me?

Replaced MAF and fuel pump, starts right up and has steady idle, but STFT are still 25 at idle. Numbers get better as RPM increases, and are within spec once around 2500 RPM

Reading live data, I noticed TPS data doesn't seem to be moving as it should, basically stayed between 3 and 6 as I was giving it pedal. And once it warms up, it was idling down around 560 RPM, which seems low

Have not seen a code come up for the throttle position sensor. Any ideas on the low idle?