1999 Infiniti I30

I am having to replace a valve cover gasket and a manifold gasket on my 1999 Infinity I 30 t (350-400)and I was told that a knock can be removed most of the time by simply replacing your spark plugs with platinum high quality plugs and wires.(200.00) I cant afford to have mine done at this time but if you have to replace a valve cover gasket that's the time to save on labor cost. So check it out ask your local shop if that will help good luck I love my car its paid for cash 3 years so and I have done the brakes and replaced 3 tires now I am doing the valve covers, manifold gasket and o ring sensor for the camshaft, and replacing a tire and a new battery it will cost be around 650.00 total but that's less than a 250.00 to 300.00 a month car payment. Which I don't have now. I am on SSDI from a Brain Tumor surgery in 2003 and I have to repair things as I can pay for them.