I have an 03 GMC Yukon 5.3 it won't go past 30 MPH check engine light flashing and has a rough idle almost dies Please help!!!!!
Did you have the check engine light codes read? If not then have them read. This will give you clues as to what is wrong with it. Post them back on here and we can help.
A flashing check engine light means that the engine is misfiring and damaging the catalytic converter. As dandy said, post the codes and we can help further. -Jim