oil in spark plug tube

First off,my sister has an 01 4 cyl accord. While she was sitting in a drive thru today, her car started shaking really bad and would get worse when accelerating. The car would do the same when revving in park but the rpms would also drop to the point where the car almost stalled out. I changed out the spark plugs and noticed there was a little bit of oil in one of the spark plug tubes. The tube isn't completely filled with oil but just enough to coat the spark plug and wire. I read online that it could be an o-ring but the tow truck driver says that it could be a blown head gasket. We're taking the car to a shop tomorrow morning but I would like to get a heads up on what you guys think so I don't get any surprises when I get there. Thanks in advance.

What's the oil look like if u pull the dip stick? When u changed the plugs did the shaking go away? Start with changing the o ring then go from there

Oil appeared normal. Once I changed the plugs, the car felt normal with no shaking until I drove it 20 feet, then it came back.

check them for oil again ?

Your spark plug tube seal is leaking you need to remove the valve cover in order to replace them and you should replace the valve cover at that time too. The shaking is more than likely a misfire since it cleared up with changing the plugs. If I had to bet the spark plug boot was oily as well and is probably a little swollen from the oil soaking I to it. So fix the oil leak then replace the plug wires and you should be good.

My buddy had the same problem for him it ended up being a broken oil ring on the piston. I would start with the rubber seal in the spark plug tube

Thank you guys for all the comments. There were misfires on all 4 cylinders. We changed out the distributor cap,rotor and also the spark plug wires which ended up fixing the problem. The terminals were burnt on the distributor cap. As for the oil in the spark plug tube, it is the rubber seal that is leaking. We cleaned out all of the oil and will be changing out the seal this week. Thanks again guys!!!