Does your OBD tool read fuel rail pressure?

 

Yes, checked this morning and I was getting 39.5 psi.

 

If you overfilled your gas tank you likely have an Evap code which will cause a check engine light. Carbon canister may be full of gas. Look for information on Evap system. There are three or four codes that are possible due to an overfill.

 

You asked about a better scan tool earlier. I'd recommend you get one recommended by Forscan, and then install Forscan. With it you can see valuable data to pinpoint the cause of this and future problems like freeze frame data, fuel trim and MAF voltage.

Anyway, since the most likely cause of these two codes is a vacuum leak, and the easiest way to find a vacuum leak is with a smoke machine, I'd recommend you borrow one, buy one or make one. I made one after watching some online videos a few years ago, and it helped me find a vacuum leak in the gas fumes purge system.

 

I actually have a smoke tester on the way, should be here tomorrow. Do I hook the machine up to a vacuum hose, put it in the intake, or some other way? Never used one before. Thanks for the comment and advice.

 

I don't think it matters which vacuum hose you put it in as long as it fits in tightly. Except I wouldn't put it in the hose for the purge valve.

Also, looking back to your original problem, "shudder when stopped", and P0171 and P0174, just want to confirm that's still the issue.

Considering all the work and expense you've put in on this "problem from hell", sure hope the smoker enables you to solve it. It does though serve as an excellent example of why pinpointing the problem before buying parts is a better approach, no criticism intended.

 

Indeed, it's a shame that I always have to learn the hard way, but at least I'm learning. Still shuddering at red lights, but the machine comes today. Thanks for the help..

 

Shuddering at stop when in drive AND in park?

Have you cleaner/replaced the idle air control valve and throttle position sensor by chance?

 

You're not the only one who has to learn the hard way.

 

Smoke tester arrived, I hooked it into my brake booster line, taped up throttle body and found that the EGR valve is leaking. It's leaking near the mount on the side of the engine, where the metal tube goes into it. Should I try to clean it since it's stuck open or should I just replace it? Nothing else was leaking, thank God.