Scrappy

I posted yesterday that my car is backfiring and seems to have a power loss. Wehn I get on the gas hard it will stumble then backfire then take off like it should. I have checked my plugs and wires changed my fuel filter and put new gas and injector cleaner in it. I have no SES light and Autozone's computer found no codes stored. The car has 33,000 miles on it and is only driven about 3 or 4 times a month it has not been modded in over a year. When I revved it earlier I got a lot of black water out of the exhaust. Any help will be appreciated. Thanks in advance Scrappy

My Mods are SLP longtubes Y pipe high flow cats, loudmouth, intake, filter and bellows. Just incase it is pertinent.

technical

It really sounds like lazy O2 sensors. They won't throw a code, but you would be able to check the crosscounts with a diagnostic scanner.