What causes surging when passing gear is kicked in?

Question

I have changed the fuel filter and air filter. 1994 chev astro van.

Answer 1

Changing the fuel filter improved the fuel flow, changing the air filter improves the air flow, surging is because passing gear is a lower ratio, higher RPM, higher torque, and to produce the power the engine is now drawing more fuel and air than it could with old clogged filters.

Answer 2

Could be a lot of things. Start with the basics. Plugs/wires/distributor cap & rotor. After that it could also be a tranny filter or low tranny fluid too I guess I've seen that happen too. Because the torque converter doesn't have enought fluid to build pressure to allow for the right gear to be selected at the right times so it will serge to try to build pressure to shift.

Answer 3

I think it is the system