If I try to start it normally, it starts after cranking for several seconds. It stumbles and BARELY runs. I don't know if it would ever run properly or not, if left to itself. If I hit the gas once, it will idle a little high for a couple of seconds and then settle down and idle correctly. If I give it some gas while I'm starting it, it starts right up and idles as it should. It also doesn't seem to have the power it should.
I just bought this car (96 Roadmaster). I'm replacing the tuneup items now. Plugs, wires, fuel filter. I've put fuel injector cleaner in it, but I have only driven maybe 30 miles or so since then.
Any ideas? Thanks.

It turned out to be the coolant temperature sensor. It was reading extremely cold and feeding the engine way too much fuel.