I took my car to the ford dealership for oil leak...now I am having a whole another...

[Reign73]

...set of problems!? I have a 2002 ford taurus,(with the oil leak problem ;which they fix) but now my engine light is on and flashing and the car is bogging down real bad and won't accelerate at all! They tell my car needs a tune up because the parts used on it,(not ford parts)were cheap and not dealer quality.They ran a EEC test on it and now are saying have: 1#random misfire code & cylinder 2 misfire code,2#found wire arcing at EGR tube also coil arcing...basically they say I need a new coil,factory plugs & wires....I'm no car expert I pretty sure this is a bunch of shit! When I brought the car there no check engine light, no car hesitation, none of that and now when I pick up the car all this nonsense is happening! I'm going to meet with the service manger monday...to give him a piece of my mind,Am I right in my thinking that they are at fault...P.S.this what fixed my oil leak (replace rh valve cover gasket and upper intake gaskets) do you have to remove the sparkplug an wires in doing this type of work because maybe when they were putting it all back together :this is how the problem started...