I have a 1991 legacy with the 2.2 liter. It seems to idle fine but when I put it in gear it nearly dies and then will miss if I try to accelerate. It will rev great in neutral but not driving. When I pull the #1 spark plug or disconnect the fuel injector there is not noticeable difference at idle but when revving the engine there is a difference. I know the car has been sitting for a few years, could bad gas cause this? Does #1 not affect idle? What gives??

If one is not firing there will be no noticeable different at idle. But under load misfires become magnified and a considerable difference can be felt. The CEL should be on. If it's not it's burned out or covered up. Search how to pull the codes and post them here.

It's probably a sensor out of whack. There are a few that make the car go into limp mode where it will kill the number one injector to tell you there is a serious problem.

 

If the car has been sitting you need to change the fluids. All of them, brakes, engine, trans, differentials, power steering, and coolant. Drain the gas tank and get some fresh gas in it. Put on a new fuel filter. And do some basics like new spark plugs and wires, PCV valve, air filter, and check around for broken/split/chewed vacuum hoses.

Ok thank you I will change fluids, gas, plugs ect and hope for the best. When I bought the car the back carpet had caught on fire due to heat from the exhaust. Has anyone ever seen this on a legacy wagon before?