Mike;
Loose header bolts,especially on aluminum heads is very common......I've lost track of how many came out on my car......that should not have any effect,except maybe blowing a header gasket now and then....Usually after every two or three track sessions,once the car cools down,I run a wrench on all the header bolts,after two or three times doing that you should be o-k, but keep checking them......
I've seen some clutch disc's loose a piece of material before, sometimes a pretty good size chunk can come off and then it will throw things out of wack, also,if your pressure plate is the type with the weights on the "fingers", you could have lost one or more of the weights and that will definetly throw things out of balance...
I know it's a pain to pull it down, but it's better to do that then have something else vibrate loose and tear up.......
At least you did not find pieces of
oil rings on your
oil drain plug like I did this weekend!!!!!!!!!!!!!!
One thing I've found out is that track time on a car is about equal to 10 times that amount of mileage on the street or MORE.......I spend at least one hour checking things on the race car before hitting the track each time just to make sure everything is tight and in good working order............
David