91 Galant GSR running rough
 

Hi guys, new to the forum so hoping you can help.

My partner's 91 Galant GSR was sitting in the driveway for 3 years without running and now it's having a few issues.

When first started (ie cold) the idle RPM will fluctuate between 1,500-2,000 but once it's warm it sits comfortably on 800rpm.

Taking off is incredibly unresponsive, foot flat to the floor and it struggles to get to 60kp/h even though the RPMs are sitting at around 2,000-2,500.

Engine has a rattly sound, and once it gets warm accelerating causes a whining sound from the passenger side of the engine bay.

The fuel pump & filter were replaced prior to the car sitting there for 3 years. (so she says)

I have since dumped the oil and transmission fluid, replaced both and replaced the oil filter.

Filled with new fuel and ran injector cleaner through the mix.

Apparently the car never had the rattle sound before (sounds like a diesel, aka low on oil but oil levels are fine using the dipstick) and it was very "zippy" so wondering what could be causing the noise issues and the issue of the non-responsiveness?

The other issues with the car are:
-Cruise control will not engage, I would check the fuse but there doesn't appear to be a single fuse for it lol
-Going up steep hills I can have my foot flat to the floor and not get any grunt out of it, however if I push my foot as hard as I can it starts to growl but still lose speed.

Any ideas?