Glad to hear that you can do your own repairs. That free factory shop manual goes into detail about each system which can help you troubleshoot problems plus it shows the special tools needed which helps if you know how to fabricate stuff out of the contents of a junk drawer. The manual recommends having a DBR2 code reader since it will show trouble codes the computer had stored when something started acting up but not bad enough yet to throw the code. One may show the thrown P0171 with a string of un-thrown codes behind it indicating what was having problems that led to the P0171 being thrown.
That B-12 is cheaper than a reader so might as well try that first before replacing anymore parts. It may do the trick and wouldn't hurt to have in the gas if it doesn't.

 

I'm for sure going to try that b12 it's the white can with red letters? Hopefully I can catch a ride to walmart this morning I'm getting tired of waiting on amazon shipping for everything.

 

Yep. White can with red and blue printing. It's the same stuff used in B-12 spray carb cleaner.

Amazon should try using the USPS parcel post since they tend to get stuff delivered faster than FedEx. I ordered the long bolt and thrust washer needed to install the crank pulley on my Neon from McMaster's-Carr on a Monday morning to find it in my mail box Thursday morning.

 

I tried that and it would barely stay running long enough. We replace the fuel pump and the fuel regulator and it still was running not so great with intermittent times of actually not being bad. He took It down the road said it ran horrible again. Got home and now it won't even start. He's given up and telling me to just sell it. Stressed because it's all I got and that's my job is driving and now I'm beyond broke without a car still. Any more ideas from anyone else would be awesome.

 

That's not good! Have you checked to see if any new codes have been thrown? Did you happen to check the gas flow out of the old filter then the new filter to see if there was any change? I'm still leaning towards a vacuum leak if no other code has been throw. It could be between the throttle body and intake manifold, something that attached to the manifold or the gasket between it and the block.

 

no new code except the code for my battering going died. I can't remember what it was like 1684 I think it was

 

Huh! I remember reading posts on Reddit's Ask a Mechanic forum where vehicle owners had running problems they couldn't repair by replacing parts only to have those disappear after installing a new battery. Know anyone that has a new battery that you could try out in the Neon?

 

you know what seems odd to me it was running fine until these new axels got put in. It all makes no sense.

 

The general rule of thumb is to inspect what repairs were done last when a good running vehicle starts acting up shortly later. Who changed out the drive axles? I've replaced both decades ago in my '89 Caravan and '95 Ford Taurus. Wasn't hard to do since the cars were raised on jack stands so had plenty of room underneath to swing a mallet and use long prybars to pop them out from the transmission.. I'm wondering if your mechanic did that from the top and managed to damage something to create a vacuum leak that gradually became worse.
Also may want to look underneath to see if the floor jack, jack stand or block of wood set on top of those managed to crimp the fuel line going to the rear. That would restrict the fuel flow with the bend possibly becoming blocked by crud. I think the fuel injectors have a fine filter to catch any crud that got by the fuel filter and developed inside the fuel lines.
Somebody did something similar to the Taurus before I got it. They managed to crimp shut a metal brake line going the rear passenger side disc brake. The car braked normally thanks to ABS so discovered later when installing new pads that the caliper had been raised to clear the brake disc and had a piece of hardwood holding the caliper piston in place.. .

 

Funny you mention the battery because the second day the car sat without being driven my battery went dead and I got it when I got he car which I found out was feb I purchased it. So I took it in and they tried to charge it and then called and said it threw it out or whatever so I had to be replaced. I have to go get the new one today.