Have the disrtibutor looked at it be wear in the shaft which ahs the
rotor arm at the end of it, if that shaft is worn you can get all sort
of problems, one way to find out if it is worn remove the cap and try
and move the shaft side to side if it moves from side to side you got
problems,when was it serviced? like replace plugs,leads,cap. oil
etc.the coil might be sparking across to something metal try moving it
away from metal,


|