06 4.4 Surge at start, profuse smoking

[RapMasterDad]

My wife's 06 4.4 (80K miles) started bucking or surging when starting to move slowly from idle a while back. It only did it sometime, so of course I ignored it and hoped it would go away. Well, I just had it in the stealership for service for the first time since the warranty expired and they wanted to do more than $7K worth of work. I told them to just do the basic service and I would think about the other things. The major parts they wanted to replace are the vacuum pump (leaking oil?), the oil pressure switch, and the front CV joints. I own several German cars, and one Italian car. I considered this price in the Italian repair stratosphere, so I decided to repair those parts myself. I have the pump, etc, but have not gotten around to fixing it.

Now, for my question. Today I was driving it through a drive-thru and it started bucking and smoking profusely. It drives perfectly above about 3 or 4 mph, but jerks starting off. Can this jerking and smoking be somehow related to the vacuum pump leaking oil? If not, what could it be other than the obvious very bad things?

Thanks.