Help, when it's cold it misses
 

When it's cold it misses as if you let off the gas before pushing the clutch in except much more severely. Almost dies but doesn't. This only seems to happen at below 3000 rpm and when it is cold. Only happens a couple of times when cold and not continuously or all the time. Doesn't do it at all when warm. Suspect head temp sensor. I am going to run a bottle of Techron, replace plugs and fuel filter. Any other suggestions. This is a 1988 Carrera 80,000 miles. This started after about 600 miles after 3 months of winter storage in temp contolled garage. Any help appreciated:confused: