Engine Mechanical problem
1999 Vauxhall Corsa 4 cyl Two Wheel Drive Manual 93000 miles

My car has been doing this for a while now. When starting up it takes a few minutes for it to warm up and for me to be able to accelerate away, if i try to go i get no response from the engine even with my foot to the floor. It sometimes happens when driving too, there'll usually be a rattle from the exhaust then i'll lose power and possibly have to change gear to keep it moving.
Serviced 2 weeks ago and nothing changed. Nothing on engine diagnostics either