When I am in 3rd gear doing around 50 I can feel the engine surge then drop back intermittenly. I am kind of guessing what the problem might be. Could be plugs, wires or coil or a combination of them.The engine seems to run smooth at idol so I am at a loss as to what the problem is. Anyone got any suggestions?

 

no check engine light at all? Checked for Vac. leaks?