Twice in the last week, it seemed my whole truck was shaking and the check engine flashed for maybe 30 seconds or so. Went to Autozone to get the code, but none existed, they said the code needs to be active. I took it the place that just completed a full tune up @ 100,000 miles. They checked and stated no history of any code and drove it for 10 miles, no results. Any thoughts?

 

If it's flashing, it's a misfire. Most common is a bad spark plug or coil.

 

Considering I just had everything replaced on a tuneup , could there be skullduggery?

 

What did the "tuneup" consist of?

 

If they replaced all the spark plugs, ask them what brand plugs they used and how many broke when being removed.