1989 Pontiac Firebird 1989 Firebird Formula350 High idle rp

Hi I just bought a 1989 firebird with 140,000 when I herd it the first time sounded great, drove it home then the problems started to kick in, when I let off the gas seems like it would hesitate a little bit, but it wouldnt stall, when I parked it at home I notcied it would idle at 1000rpm and would jump a little, also with it running and sitting I started to notice a smell of gas, the car wont stall, also it has been sitting for a few years, I brought it over to my buddys house to give it a tune up got sparkplugs, distrubitor, fuel filter, oil filter, air filter, and pcv. We didnt install any of it yet because we wanted to see what the problem was we hooked it up to a prlbem reader(idk wwat its call) got error code 13, 22, 33 he tinkered with it a little and got it down to 500rpm at idle and smelled a little less of gas. He told me to go get a throttle postition sensor and a idle air controll motor. And then do the tune up at the same time and he said it shuold be good. Im basicly asking for any second opinions. Is that a good start or any other ideas? Ty for the help !