Help me find out the problem

[GasSavers_BIBI]

Ok so I did tried a civic vx 92 with 94 000 miles and the owners ask 2500$. The car looks clean, no rust and interior is ok. The wings of the back have been repainted this summer. The front brake will have to be changed. The alternator is new, gas tank too. The distributor seems to have no more than 2 years, and the radiator too. The engine is running very well and car started easily.

BUT, their is a problem. First of all, in neutral, the idle is erratic, 1000rpm to 1400rpm to 1000rpm on and on. Second of all, when accelerating, the car will severally hesitated and the car seems like to bug and you need to push the throttle. Its probably not just the engine going in lean burn mode. The spark plugs have been changed and might not be the good ones, but I don't think its only that, maybe the O2 sensor, but there is know check engine. So I'm wondering what could it be to see of the car worth it, or if the problem is too major. Anyone have a thought on this?