back again guys. Okay, so this is a problem that showed up in the last couple months. I've been messing with it and having no luck at all trying to get it to go away. When I start the car it is supposed to shoot up to around 1800 then drop down to idle. problem is, it doesnt always do that. more and more, it shoots up to 850, then drops down to about 500 or lower. stalls a lot, and smells like gas. but if I drive it a bit, it idles much better, and wont stall anymore.
I've replaced the IAC twice, cleaned the throttle body, just replaced the battery this morning. No codes but 12. Computer was replaced last year.
Motor is a jasper 5.7 reman. was put in in January. the entire fuel system was gone over last year, and injectors, fpr, fuel pump, fuel filter, and gas tank were all replaced. Spark plugs were changed in the last 6 months as well.
Where should I go next. This hasn't been a huge problem yet, but I cant stand hearing my car struggling to even run after all this work and I want to get it going right. until last month it started with just a quick blip of the key and idled great. now... not so much.

 

well here's an update:
I pulled my cap n rotor, and swapped out my coil with a spare to see if they were the problem. no dice, everything looked fine, and idled the same. BUT! I was thinking hey maybe I need to just pull a vacuum line temporarily (since that'll make the car idle higher) So I pulled the brake booster vac line to see. Idle shot up like I expected, but when I popped it back on, the idle stayed up around 1000-1100, where it should be when it's cold (which it is right now). stopped the car and restarted, and it started like it should. wtf is this? I feel like i'm making some kind of progress, but I don't know what exactly. help?

 

update 2:
I just went back out after letting it sit for about 10 minutes, and it started up perfect again. shot up to where it should and dropped to about 1000 to idle. I was expecting the problem to be back. what could pulling the line of the brake booster and then putting it back on have done to make the engine idle right again?? could I have a bad brake booster? would that even make sense? I'm actually a bit more confused than I was before.