2004 Chevrolet Colorado Q&A

2004 Chevrolet Colorado Question: with sea foam in the vacuum smoke came out the top of heat shield?P0171code

Just after I had glass packs muffler put in and cut off and turned down the following days had a reduce in power and little of a rough idle where's The best place to startlooking for tha problem? -
Answer 1
Are the converter(s) still on and in original location? Changing backpressure will affect performance. -