Hesitation in 6th gear

[tlark001]

I have a 6spd 94 Z28. I have had no problems with it, but when driving on the interstate today I noticed something strange. It was driving fine but when I shifted into 6th gear at about 65-70mph and tried to accelerate it began to "stutter". I shifted back down to 5th and it was fine, but going back up to 6th caused the same thing to happen. Any ideas on what my problem could be???? Thanks for any help!

[tlark001]

Update: needed new cap & rotor. eventually had to replace the distributor.