1994 Questions for all other cars Blasting in curburator

Engine Mechanical problem
1994 Questions for all other cars Engine Size unknown Two Wheel Drive Manual 15 miles

I have a Maruti van of 1994 make. My cars dose not move freely, and at the time of starting at mornig move very slowly and start to blast like gun. I, v changed spark plug, washed curburator, changed valve/sheet, Piston Ring, Plug cord. But.
please give me the right solution.