is there a generic OBD connector in your platz?
i think first of all you should remove the spark plugs and inspect their state. If they are oily and black, you have a lack of air, and/or low combustion due to faulty spark plugs. Easy way to check if they are black and oily is by borrowing one from another vehicle (if you dont want to buy just for testing) and trying the new one.
If your spark plugs look clean and slightly pinky white then the combustion should be ok, and the problem lies elsewhere.
I would check air, and fuel filter, and MAF sensor. Remove the connector from the MAF sensor and see if it improves the situation.
If your spark plugs show a problem it could also be due to faulty O2 (Lambda/Oxygen) sensor too, which is in the exhaust manifold usually.
I am hoping the you have already sorted out the issue though cos just noticed that your post was a while back.
anyway, hope it helps.