VT commodore has trouble turning over

[Tuhoro]

Hey guys had my VT for about two years she ran fine the first year or so but these past few months I’ve had some real trouble with it turning over. The flat battery signal popped up and would cut out on me whilst I’m waiting at a light or if I’m just idle for to long, so I took her in n got a new alternator, crank shaft sensor, new belt, new battery and fully serviced, she ran fine for a week or so no battery light any more and she’s a lot smoother, but it’s gotten worse now she doesn’t want to start if I drive her for the day even just going to the shop I had to leave her at Cole’s for 9 hours cause she wouldn’t start so I gave some love taps to the starter motor and she eventually started, also if just slowly creeping thru traffic or at the lights she will randomly get a rough noise like she’s going to cut out and she has a few times twice while I was driving real slow not sure what it could be I’ve noticed when I press my breaks the light on the original radio goes dim is that normal any help would be appreciated thanks guys

 

[RiffRaffMama]

I had to leave her at Cole’s for 9 hours cause she wouldn’t start

Last year I left my car at 7-11 in Werribee for three days because I blew the head gasket whilst driving on the Princes Freeway and I categorically refused to leave my car on the side of the freeway to get all the windows smashed like all the broken down cars do. I live 200km away from Werribee, conveniently the exact distance the RACV will tow your car if you have their top roadside package. I did not have RACV coverage of any level, however, it takes about 10 minutes to sign up online.
Did you know?: the waiting period before you can use an RACV membership is 2 days. Next time, get someone to drag flat tow your car to somewhere (in the dead of night) that's open 24/7 like... I don't know... 7-11, park it out front in clear view of the counter, remove the battery and number plates, leave your console and glove box open, lock your car (probably do the remove the battery/lock your car bits the other way around) and go home for 3 days and for the grand sum of $25 you can have an overnight stay in a hotel, taxi trips to the hotel and anywhere else you need to go, a 200km taxi trip home and most importantly, a 200km flat bed tow for your car that has been at the Kwik-E-Mart Babysitting Service for 3 days. Tell the Mrs you're taking her out for a romantic night at a hotel. Get a lift there from a mate "so you can have a few drinks". Don't say anything about your car. Reap the rewards for weeks.
Or you can pay $600+ to get your car towed and bum a lift off a mate if that work better for you.

As for your problem - I know you said you got a new alternator, but your description sounds suspiciously like a sh*tty alternator... was it a new one or a rebuild or just second hand?
My second thought is fuel system problem - blockage, fuel pump, relay... Are you on straight petrol or dual fuel?

 

[shane_3800]

Possible DFI module, if it's running rough.
Maybe pull it off and clean the back and clean the mounting pad.

 

[Forcedvp]

And check your earths.