Forgive what is probably a really stupid question (my counselor in high school refused to allow me to take auto shop). I have a 74 El Camino and I'm trying to figure out everything that needs fixing so I know if I can afford it or not. When I start her I need to pump the gas but she does start usually with no problems but once I get her in gear i have to really give her a good bit of gas or she dies (stalls I guess). Usually I just throw her back in park and restart and just try again and it's fine. I haven't had any problems shifting gears (it's an automatic) and she handles the freeway just fine (except one problem last week but after I left her to sit about an hour she was fine, it was a weird chuga chuga chuga noise and she acted like she was going to stall or was running out of gas even though there was half a tank). About 60-70% of the time when I turn her off she does this weird thing, like this rumbling "I don't want to turn off, lets keep driving" sound and she'll shake a little (although not any more than when she's driving).

Girl logic tells me that the ignition is really only to start the car (hence the term starter) but I know cars go by guy logic so, could that be the problem or do I have an expensive transmission problem on my hands or something else altogether?

The guy I bought it from said she needed the engine rebuilt so is it just a problem relating to that? (He did kind of lie to me about a lot of stuff, but it was all stuff he said was ok, so I don't think he'd lie and say something was bad when it was actually good?)

p.s. Sorry for the "girly" sound explanations.