i just replaced my tired 307 in my 70 chevelle with a 350/330hp crate motor. timing has been adjusted, carb rebuilt, and vacuum leaks checked for. rpm's fuctuate at idle nearly 400 rpm and when i try to drive it surges at low speeds. it tends to die at stop signs and under loads. i unhooked all the vacuum lines and plugged them up. it seems to idle higher when i disconnect the trans modulator. could this be a sign of a vacuum leak at the modulator? any ideas? thanks for the help.
Rich
Rich