2001 navigator

[lgj3]

I have a 2001 navigator that has 70k on it and it has a problem with the compression on the #5 a nd #8 cylinder any ideas . the only problem that its was having was that it would Idle rough

[pepsi2185]

You said it has a compression problem? Is this from a scanner? Are you sure its not the igntiion system. If the plugs and wires ahve not been replaced yet, that is notorious for giving you that effect in any vehicle.