1984 Questions for all other cars Very weird problem

Hey. I own a 1984 VK Holden Commordore. It was off the road for almost 6 months due to a dizzy issue. I bought a brand new dizzy, popped it in and finally got it running again. I drove it around for abit under a week and it was perfect. Lately, everytime when i apply throttle and also in idle, it runs very rough. I Replaced the spark plugs(which needed to be done).. no change. I also changed the fuel filter thinking it would be the best thing seeing as how it was off the road for a while... still no change. Now it is only getting worse. It's hitting a complete flat spot whlst driving and even sometimes stalls in traffic. What's weird is that during the cold mornings, she has no problems. Once the temp picks up outsde and the car warms up abit, she progressively gets worse. I have a feeling that it could be fuel related but i don't want to go out and waste money on parts that won't fix the problem. Your advice will be very much appreciated.

Thanks,

Az