S13 DOHC KA not running right

So this isn’t my car, just helping out a friend.

The car seems down on power, and when driver along when you clutch in the rpm’s drop to like 250, then back up (almost like it is going to stall).

I have been told to try a few things. We checked the MAF (it is clean, has been extra cleaned, and tried another just in case). Issue is still there, but the power seems a bit better (was running a little rich before, now seems fine).

Varun said that it could be fuel pump or sending unit. Does anyone have a good way to test this theory?
Checked the battery aswell, it’s fine.

Anything else i should check?

if it was a fuel pump I think it would cut out on acceleration, not decal.

I agree with BK on this. This is a common problem for KA’s. From what I understand it could be a bunch of problems but what i would do first if a full tune up on the engine. New spark plugs, cap, rotor, coil and wires also grab a new o2 sensor. run some injector cleaner through it and go from there. Even if this doesn’t help the problem its a good thing to do for these engines and it will cost you less then 200 bucks in parts. It is all stuff you can do your self too.

I had that same problem. Whenever I would clutch-in while driving, the rpm would drop supper low and even stall. It ended up being one of the last things expected, it was a bad speed censor. Try unplugging yours

The car has just had a tune up (was doing this before). I’m going to check the gap on the plugs too… be surprised how often it’s not actually set. What is the plug gap supposed to be?

Drift99, is the speed sensor in the same spot on the S13 as the S14, near the back of the tranny?

im not sure about s14 but yeah s13 has it at the end of the trans