[TR] intermittant rough running

[tr3bob at cox.net]

Hi fellow listers,

It's been a while since I've had to rely on the wisdom of the list, but I could sure use some help now.

My TR3A (TS81398LO) has been running great (for the most part) but I've had this recurring intermittant problem that's really bugging me.

I'm running at 3000RPM and suddenly the car stumbles.....as if misfiring a cylinder. It mysteriously smooths out then happens again. It eventually deteriorates so that it's stumbling 80% of the time.

I pull over, pull the plugs and find them a nice straw color. Fire it up again....get home and put in fresh plugs. Viola...problem fixed. 

300 miles later I get the same symptoms and replace the plugs again. What gives????? I really could use your help. The plugs aren't expensive, but it's bothering me.

TIA

Bob Stahlbush 
   and get to a and check the  d  on running on 3 cylind