C230K98DRIVER

Hi guys I'm having the same problem code p0400. My 98 c230 runs rough at idle, low speeds or at a stop while on D. I have also received a code p0302 misfire cy 2 for the first time. I have just changed my spark plugs for the first time 2 days prior to the CE light. These codes occurred together the same time after checking on my spark plug 2 because the boot protector was replaced and wanted to make sure that is was not stuck on the spark plug like the old one did. The spark plugs were changed from the BOSCH to NGK Platinum's. I may have unclamped the FAM from the air filter box about 2 or 3 mm while engine was running and also replaced the front side EGR linking vacuum hose which was broken into 4 small segments which were joint together by rubber hoses, and replaced them with a 4'' plastic straw from a spray bottle. Any advice is great full.
Thanks for reading.
Please HELP!!!