Try disconnecting the oxygen sensor or throttle position sensor and take for a drive. Doesn't have to be long, just far enough to do some shifts, maybe get into 4th or 5th... are the symptoms the same or does it seem to drive better?
sucking sound sounds like air, maybe a vacuum line or something. I know some of the hoses can get tiny holes hard to find unless you take them off. Like the ones up near the throttle body. I think one of the larger ones may do something like this...?
JJ