i have an 87 lt300e that seems to loose spark... it will always idel just fine but when given throttle it will stall. sometimes though it will run just fine and will also run without problems wide open on the pavement. problem happens when tryin to come off idle or cruzing at low speeds. if condition happens while moving it will most often pop out the tail pipe and come back to life. carb is working fine and has been rebuilt. any help????