Nissan Repair: NISSAN ALTIMA 1997 ENGINE RATTLES, nissan altima gxe, vacuum hoses

Question
My Nissan Altima GXE 4D Sedan 1997 engine rattles. Whenever I am on Park, or taking reverse it would rattle n fluctuate in fuel emission. Last week I did engine tuneup worth $260, they changed all the wires, cap, plugs, but it would still rattles. Once I am driving on 20 mph, it would ride smoothly. Can you suggest whats going on with my car?
I have 198000 miles on it. Is it something wrong with the timing belt?
Please guide me...thanks.

Answer
hey chintan, you may have a timing issue but i don't think it has to do with the chain itself, you may be off a few degrees on the distributor.  when you say that it rattles and fluctuates, are you talking about the rpms?  i would have the iavc serviced.  it may be clogged.  another suggestion is to check all your vacuum hoses for any leaks.  the smallest leak will cause a headache of idle issues.  good luck with this and e-mail me your findings.  xxp_sebby@yahoo.com.  thanks!