My 240 84 gl has a irregular running condition. The car will suddenly jump in rpms appx. 500-700 all by itself.At times it will stumble and stall out when coming to a stop.Otherwise it has a steady 800 rpm idle. My corrective action to date: I cleaned and gapped plugs,cleaned out the throttle body assy. and the oil breather flame trap and related hoses, swapped out the following from my 84 parts car: cap, rotor,AMM,ignition wires,coil,air idle pump,as well as the fpr. I installed a new fuel filter.I also checked all my vacum lines and replaced the cracked air intake hose assy.Some observations: Now I notice that my exhaust smoke is a white/grey in color. I have been reading the post the past two months to troubleshoot the problem so my weather temperature conditions here in Penna. have been both hot and now cold and the trouble still persist. I have not tried to change out the relays, fuel pumps, or the computer as of yet. I would appreciate some input