My car is a Toyota MK4 NA Supra and it has a problem I don't understand. When I push the throttle gently, whether in park or in drive, it gradually builds revs and moves but when I push it hard i.e flat out, it acts like it's misfiring/backfiring and doesn't move. I have to feather it ever so gently. It's way worse in the mornings when it's cold. Please I need all the help I can get.
Is it my spark plugs?
leaking vacuum? etc
Thank you guys!