RPM meter revving up and down during idling

[-lanz-]

I sent my car to a workshop to fix a vibration problem.
The next day,the mechanic called me and said my car unable to start and might be the distributor spoilt.I like WTF,it was fine till i leave it at the workshop yesterday.I pay a visit immediately to check it out.I tried to start myself and was not successful either.I don't know why the distributor spoilt suddenly.I ask the mechanic to replace a good distributor and he charged me RM350 for that.The next day he called me and said my car is ready.During driving back home,i found that the rpm meter is like revving up and down frequently(during idling).So,i suspect something wrong with the distributor.Back at home,i opened the bonet and found one of the distributor cable was plugged off,i plugged it back and check the rpm meter,now the revving is gone.I did a test drive and the revving show up again.Found the same plug came off,i bent the plug socket a little so that it can fit tightly to the distributor.But still the rpm revving happens with less frequent.I haven't sent it back to the workshop.I want to find the root cause first before send to the workshop.Any idea guys,where & how to check?BTW im driving SE(AE92)

 

[Supra_Fanatics]

Best send back to the workshop to fix it. If still there after that, suggest go other workshops. Not sure if they are doing what I'm
thinking. Some bad apples they tend to spoil other things just to get you to get back to the workshops a few times.

Not saying that workshop u go is like that. Just possibility is there as I experienced once before. My engine hose putus but with
a nice cut edge... Went to that workshop 4 times in a month to repair one after another.

After that we left and go other workshops instead.