1999 dodge v10 magnum misfiring without throwing codes

lowcudd

Hey scotty long time viewer first time questioner. I just bought this 1999 dodge for really cheap with relatively low mileage (130,000). the truck is in really good shape frame and body wise but its missing at idol and doesn't run as hard as it should. none of this really bothers me that much as its my second vehicle and i just needed a cheap truck to haul supply's with. Problem is that it failed the sniffer test during my emissions test, because its running to rich. The truck isn't throwing any codes but, I've replaced spark plugs and CO2 sensors. checked the fuel pressure at 50 PSI, i found that the MAP senor was loose and was missing a bolt. i thought it might be the plunteum gasket but the previous owner mechanic has just recently replaced the plenteum gasket and he told me it would run lean if that was the case. I've also checked for vacuum leaks though I didn't use a gauge. All of this has definitely helped the truck run but i don't think it will pass the sniffer test with the miss fire at idol because of the unburnt fuel. Any advice is welcome.

Thanks Logan