Sounds like you are running real rich. Do you notice raw fuel smell? If so it could be a list of things. First off get it scanned. Just because there is no engine light does not mean there is not something wrong. Here's what I think you should check. Bad fuel pressure regulator, egr valve and/or solinoid, bad opti, spark plugs or wires and lastly check your MAS sensor. A scan should tell you what's bad sesnor wise but the fpr, opti, plugs and wires are gona have to be checked by someone who knows how to check these items. I'm not saying all these things are bad but anyone of these could cause your issue. Hope this helps.