Yeap you're right. Iraq invaded on August 2, 1990 and got kicked
out of Kuwait on Feb 27, 1991. Bit lazy to check the dates up
And yeap, I failed to consider what if Singapore was capable of
holding on for quite a while. In that case, what you said about
American naval and air assests giving our ground forces a boost in
the arm would be right on
Still, I feel that what WWII has taught us is that Singapore cannot
survive for long if cut off from her food and water supply in
Johor. Hence, until we secure self-sufficiency in water at least,
Singapore has to fight a short war... and win. If Malaysia manages
to protract the conflict, we're as good as dead.
If you're talking about US help after Singapore
falls...i still doubt we need a lot of their ground troops,
assuming the remnants will be taking MAF on out in the streets,
there'll be heavy urban fighting. They will realise it's a non-zero
sum game, and that will probably deter any invasion in the first
place.
I haven't served my NS yet, but i have faith that Singapore can at
least hold out in defence for at least 2-3 weeks before
capitulation. (Blind faith perhaps?) 
The same thing applies here. If Singapore has fallen, there's
not much point in carrying on the struggle aka Iraq or Somalia.
With no food and water, the Malaysian army does not have to engage
in bitter FIBUA with remnants of the SAF. It just has to pinpoint
and isolate pockets of opposition and wait out the war, like how
the US encircled Iraqi cities instead of entering them during the
invasion last year. Of course, I'm not sure how effective this
strategy would be since, unlike Iraq, Singapore is so heavily
built-up. The MAF may really have to do FIBUA if they kena heavily
attacked by us with MGs, LAWs and mortars and got no place to take
cover. But still, given our resource constraints, we wouldn't put
up too long of a fight. Political will wise, I'm not very sure. We
have a pragmatic nature and would not have the stomach for heavy
casualties. However, since the invading hordes may bloody well rape
our women and rip us bare (think the anti-Chinese riots in Jakarta
1998, except on a bigger scale), I think I would fight. Indeed, I
feel those NSmen with families would really fight in wartime since
everything they have is here.