when cold engine starts up beautifly until the tach starts jumping erratically. while driving, the car tends to buck (no combustion). This has been a problem of mine for a while so i'll take you through all the things i have done to it.

1st try
cap
rotor

this fixed the problem for about a week

2nd try
ignitor

(noticed some casing comming off wires leading to the ignitor)

fixed the problem for about an hour and a half

3rd try

replaced damaged wire going to ignitor

didnt do anything

4th try
main relay

car runs better but tach is still floppin all over the place (not engine)
today i cleaned, disconnected and reconnected the harnesses going to the distributer, as well as jiggleing the wireing going to the main relay. car ran like a champ for like 5 miles and 2 starts then it went back to the same symtoms. what could the problem be?



after replacing the main relay misfires and the erratic tach movment OLNY happen when i hit the gas. when its cold everything works perfectly when it starts to warm up the tach begins to go up erratically (never drops below actual engine speed. after about 5 min of warm runnning i give it some gas and it will bog (misfire)

 

i had the same problems as you did too. But how i fixed my problems were taking off the distributor cap off and then took out the rotor in it. You notice inside the distributor there's wires that are plugged inside it. Well as for me i took an aligator mouth and just squeeze the plugs tighter so there wouldn't be any loose movement. Try to see if that might be the case.