Hi up until today my 5.2 SL has had zero problems. Car ran great, has 94k on it.

Today I go to start it and it won't start. Battery's toast. Okay fine. Jump it still won't start. Not the clicking but that cranking noise too like it really wants to start. A few times it does start and then instantly dies. Fuel light is on, add 1.5 gallons. Someone says hit the gas while you crank it I say ok. Car starts and revs perfectly fine. The second I let off the gas it INSTANTLY dies.

I try this again and keep it revving high for ~10 seconds. I let off the gas it instantly dies.

Someone said it probably has something to do with the fuel lines.

Think is yesterday I drove around for almost an hour and had ZERO problems. Parked it in my driveway like I always do and that's it. Hasn't seen water or a lightning bolt or a neutron bomb. Not sure what happened or how to fix it, but this is fairly annoying.

If I have to bring it in, any ideas on costs to repair?

 

First I'd do some tests at home.

Go to an auto parts store (a good one, like Advance or O'Reillys) and ask for a fuel pressure tester. Should be a gauge looking thing with a fitting on one end (for the fuel rail test port) and another that is just a tube leading away (drains excess fuel out of gauge when finished). Also while there, grab a Haynes manual. Follow the fuel pressure test procedures outlined in there. Very easy to do, takes literally less than an hour to do. That should tell you whether you have a fuel issue or not.

The reason why I am telling you to follow the procedure in the Haynes manual is because the Haynes is handy to have for any repair situation. Tells you how to test sensors, fuel pressure, cylinder compression, etc., etc.

 

based on your description that it runs when you crack open the throttle and dies when you let off the throttle, its most likely the IAC, idle air control. its responsible for maintaining idle by opening/closing a pintle into an air path around the closed throttle plate. its a common problem. about $45 at any parts store. its on the back of the throttle body, 1 elec connector and 2 #25 torx and about 10 minutes to change. don't forget the o-ring. its a little hard to reach. its easier with air cleaner off, but after you've done it several times you'll see its not even necessary to remove the filter. search on IAC for abount a million posts.

 

before you test the fuel pressure or the iac you should swap your horn relay for your asd relay (if your horn works) and see if it will crank. i don't know what the asd relay does exactly but it will make you have a crank and run under throttle and die without throttle situation. and its a free 30 second test that you can do before you blame the iac or fuel pressure. a couple years ago i replaced my iac when my problem was the actually the asd relay. if that isn't it then go with what dvaughan and jasonw said.

 

Totally agree here , and I'll go a step further . Remove the throttle body , give it a good cleaning . Typically , the AIC will clog with carbon . Replacing the sensor doesn't clean the area it seals against , its hard to reach as said (mirrors might help). This is a great way to ensure you'll have plenty of trouble free miles again .BTW , replace the TB gasket .

I just did mine recently as my cold idle was rough , not anymore , smooth as silk at 180k . You may find a good cleaning will be all you need here . Expect rough idle at first , but once the AIC dials itself in , it will return to normal . There's a slight learning curve it has to go through , new or used , they wil react the same after being removed . Be gentle with the sensor , no pushing , pulling or twisting the pintle .

1 can of Mopar Combustion Chamber cleaner and an old toothbrush is all I ever use to make things spotless . $7 a can for the Mopar CCC