I partially filled up my 2001 Nissan Pulsar last week, and ever since it seems to be running roughly. It noticeably shudders at start-up and when stopped, as well as being sluggish to accelerate.
Would it be reasonable to attribute this to bad fuel, or could there be another issue that needs addressing?
It could be due to bad fuel. Run it out as best you can, or drain the tank, and refill with fresh fuel from another servo, preferably one that sells a lot of fuel so you can be confident the fuel is fresh.
If it still does it then look for other causes, such as fuel filter, fuel pump, air filter, throttle body, spark plugs.