Lean at 70 mph?

[Effieman]

The check engine light turned on in my 98 Ranger when driving down the freeway at around 70 mph.
Got home, checked the codes. The P0174 code was set and the P0171 was pending. The freeze frame data said the long term fuel trims were at 25 and 23.4.
The truck was idling just fine though. Bought a smoke machine (that I've been wanting) and found the vent(?) on the IAC and the air filter box were leaking. Plastic solved that, but then I had a leak all around the EGR valve. It seems at the crimp has given up.
First question.... Is this normal, or is it a bad crimp seal?
If it's a bad seal, could I use RTV around it?
I ask that because I tried to get the EGR valve off several years ago and even after using WD40 on it for 3 days I couldn't get it loose.

After that (it had been several days waiting for the machine) I went to clear the codes. It had gotten another new code, P0102, MAF circuit low. Tried taking the connector off the MAF, and it didn't want to come off. But (for) now the truck runs better. No more bucking when cold. Thinking bad connector wiring(?). Gonna get a new connector as the old wiring doesn't seem to be in the greatest of shape.
Anyways, any recommendations on how to remove the connector? Had this problem before, but after fighting with it for a few minutes, it finally came off....

 

[SenorNoob]

I'd be tempted to try to re-crimp with a pair of pliers, if I thought the crimp was bad.

WD-40, or at least the original stuff, is not a penetrating oil. Try some PB Blaster, or better yet make some ATF/Acetone mix.

The WD-40 you have with repeated sprays and lots of wiggling get that connector loose. It probably has a fine layer of dirt in it.

 

[Effieman]

I thought about using pliers too, but figured RTV would be easier to get the 'hard to reach' backside close to the engine.
Just bought a gallon of ATF and have some acetone. Is a 50/50 mix good? Never heard of that before. Do you know if it might it also work on the connector without harming the plastic?

 

[Snoranger]

It’s normal for a little smoke to come out of the IAC vent while smoke testing. If it’s pouring out, then it’s an issue.