Alternator bad?

Ok here it goes…I left my lights on and my battery died, so what to do? I push start it, it starts right up. I then has a problem reving, and I step on the throttle and it hesitates. The dash lights are dim and the radio wont work, the head lights are dim as well, but are on. It wont rev past 4000 rpm’s. I heard a trick to tell if your alternator is bad. when the engine is running unplug the battery and if the engine dies then you alternator is bad, well I unpluged it and well it almost died intil I pluged the battery back in. Is it really my alternator? It does have 185k miles, so if it has died it wont surprise me.

does that trick really work? which battery cable to unplug? or both

so I hear, I will find out, I unpluged the neg terminal

thats not really a good “trick” to try. if you undo the ground, where is it going to go? just get yourself a volt meter and test it or go to some auto store like autozone, pepboys etc.