stalls when gear is selected

hello all,

i recently purchased a 628 csia, its almost perfect but for one real problem:

when i select a driven gear from park or neutral, the revs drop, this in itself isnt a problem but sometimes, the revs drop low enough to stall the engine.

can anyone tell me where to start looking!!

first look for inake air leaks [cracked or broken vacuum hoses. when was the last thorough tune-up ? If it was recent, this sould have been addressed then.