hi!

check in following order..

air filter.

check the camshaft if nock number 2 is damaged. (very often bad).

valve clearance.

check inj. pump timing.

compression test. at least 20bar with differences MAXIMUM 20% between lowest and highest.

repair the injectors, if u are going to add anything to the fuel ADD 2 STROKE OIL!! fully synthetic.

maybe u have to change the injector if it is old and very bad
DNOSD 265 will fit and work very well on your car, need to be set to 115bar-120bar(new inj. 120bar).

hope i helped u on your way!