VS Caprice 5L - Idling/Hunting Problem

[jgtoranalc]

So my mate has VS Caprice with a 304. His problem is that it has a fluctuating Idle (or it's Hunting at Idle) and when accelerating the Revs fluctuates. I seen the needle fluctuate sporadically when accelerating only at certain revs. If that makes sense.

Previously he got told to replace the Fuel Pump and Fuel Filter. Which he did replace. He said it ran good but only for around maybe a few drives it came back.

I said to him to have a look at the dizzy and rotor button. It did need replacing so we did it. Problem still exists.

What do you reckon he should do next? I wouldn't think it would be the Timing but we are going to check it anyway. We have looked for loose Vacuum hoses but all the ones we looked at are fine, maybe we missed one common one that someone else has come across.

Note: I replaced the Dizzy Cap and Rotor Button today, I drove it and didn't really notice Hunting at Idle after the replacement but It did have the Revs fluctuating on Acceleration. Then I let him drive home. So hopefully we may have fixed the Hunting problem. I won't know until a few days.

 

[Deuce]

My thoughts are:
Check IAC & TPS,
Easy service items like air cleaner, plugs, oil & filter etc.
Check vacuum hoses again.
Transmission fluid level & condition.
Possibly the ignition module?
How dirty was the old fuel filter? could there be crap in the tank getting sucked through to clog the filter or pump?

 

[BlackVXGTS]

Did you get him to check for fault codes (since you have them documented in your post)? I was leaning towards a TPS problem, but when I read about revs fluctuating, it sounds like it could be coil related.

 

[jgtoranalc]

So months later in October, my mate got it checked out by an Auto Electrician and they tested his Ignition Module. They found it was causing the fluctuating revs.

 

[VS_Pete]

Thanks for letting us know:beer chug: