Opti 150 stumble

[rsw21282]

I have an opti 150 05. It starts and runs but stumbles I hav changed plugs, air press good, fuel press fluctuates as motor stumbles, have changed low press fuel pump, mech fuel pump is good, cleaned the vst, checked connections for coils, using plug light checked spark, and gas is new. Primer ball stays firm

Running out of ideas, help?

 

[rsw21282]

Re: Opti 150 stumble

Also have checked tracker and fuel reg valves