I have an '06 XLT with the 5.4L engine. I did the DWV mod last weekend and have lost a few MPGs. Is this normal? Thanks for the help.

 

I did my gotts (pretty much the same concept) about 2 weeks ago and no noticeable gas mileage increase. More power and no factory lag!

Is the MAF clean? Did you disconnect the battery for about 20 min. so the computer adjusts for the increased airflow? Clean the MAF with MAF cleaner, I assume you put a clean air filter in. Most of all, disconnect the battery cable and take it for a drive at different speeds so the ecm adjusts.