94 E250, 4.9. Stumbles and bucks while accelerating. Changes many sensors and ignition switch. Ready to push it off a cliff, EXCEPT I discovered that if I rock the keyswitch forward slightly while I am accelerating (obviously not enough to engage the starter), the problem disappears. I can hear a relay pull in when I rock the keyswitch forward, but I can't find it (narrowed it down to somewhere on the driver side front down by my feet). Also when I rock the keyswitch forward I lose the radio, speedo, turn signals, blower fan, and the tranny still hits all the gears but it shifts hard. There are no codes except for VSS which I changed. I think the code has to do with the speedo cutting out when I rock the keyswitch. Any help greatly appreciated.

 

change the switch then
sounds like you found the problem
you have some bad contacts

 

I changed the switch. It's not the switch. If anyone knows what/where the relay I hear when I rock the switch, then I can power the relay direct and see what the results are.

 

odd, you wiggle the switch and the symptoms appear

 

I had a boat with a faulty ignition switch, so I know what that's like. I'm not wiggling the keyswitch; I'm rotating it toward the start position while the van is running (but I'm not rotating enough to engage the starter. When I do that, a relay is either kicking in out dropping out of a circuit (I can hear it "click") and the van runs fine, but there is no radio, no turn indicators, no speedo, no blower fan. When I release the keyswitch, the radio, turn signals, speedo, and blower fan all work again but the van starts bucking and hesitating. My theory is that the relay I hear is causing the faulty sensor (or something else) to be by-passed. I want to isolate it to test my theory.