A/C causing hiccups? Any thoughts?
 

My 2004 XC70 seems to have very slight hiccups at highway speed when the A/C is running? None when air is off.
Volvo dealership did not find any codes and obvious problems, and told me it's probably the plugs?
Whats your opinion before I either try to change the plugs out, or have someone do it for 200.00 (estimate given by two shops)

Thanks in advance

Art

Usually is plugs or plug wires... Or maybe something else like the distributor. Most likely it is just the plugs though. Start with replacing the plugs (do it yourself...)