Next move should have been the first move
Surging is usually insufficient fuel to maintain a constant speed
Surging at idle but not WFO = blocked idle circuit
#3
StarTech
It might need a slight adjustment to the idle mixture screws. These are access after removing the welch plugs covering them. On the following image the needle (PN16187-7002) are under the welch (PN 92066-7009).