I have an old Mitsubishi Triton Utility 1993. It has a 4g54 4 cyl petrol engine with a carby. No computers or anything like that to check error codes.
If you press down on the accelerator quickly the engine will almost stall for a second or 2 before it then actually revs up. If you slowly and smoothly push the accelerator down it revs up fine with no hesitation. It only happens when it's warm. Also after sudden acceleration it backfires more often than not.
I've replaced the plug recently and it doesn't happen until the vehicle is warm so I don't think it's the electrics.
Given that it only happens when it's warm I am thinking there must be a vacuum leak and for a moment it sucks in too much air. I can only assume that once warm one of the hoses or connections expands a little and introduces a leak.
What else could be causing this sort of issue that I could investigate before I have to try and replace all the vacuum tubing?