..my 92 Dakota V8 was selected 2 times in a row for  "test only" smog ll shake down.  It passed both times and came back cleaner the 2nd time due to a fresh oil change and new air filter.  But I got hit 2wice back to back.  Even the test tech eas surprised to see me back.  It's supposed to be random..but?? 68.00 bucks just for the test plus reg.fee.  If I could go to my local gas station for a test it would have cost 29.00 for the test.  Even wit 96k miles on it it's neary as clean as a 2006 said the smog tech. Slightly more noX everything else was way under the limit. Elevated nox may hve been the egr valve port.  It has a new egr valve in it so the port my be dirty.