Help-86 240dl volvo cat converter- how long they last?

[joeyroberts]

Hey Volvo Mechanics!
My previous posts was in regards to my 240dl, stalling, and having poor acceleration and being ok in the morning, and not ok when its hot.. blah blah blah.
Last night I was going through the reciepts of repairs done by the original owner, I found something interesting.
I just recently replaced Cat Converter, as my mechanic found it in need of (He showed me what was left in it and it was just a small piece of something shaped like a chared rock, which was making the rattle sound. So he gutted it untill I took it to a muffler shop for replacement.)
At that time he had replaced; temp switch. fuel pump /filter (both intank and main),
the head pipe into the intake manifold was cracked and he replaced it.
crake shift pully and some other stuff.
$1,200 later still dosnt run like it should.
ANYWAYS...
I noticed that the original owner had also replaced the cat converter in 1996, about 30,000 miles ago. 127,00 on it miles when he had it replaced now
shes pushin 160,000 today. I thought Cat Converters were supposed to last like a long long time. What would cause the frequent replacement of a cat converter? and just after the original owner did that, he replaced the timing belt, had engined tuned, replaced spark plugs and cleaned the injectors, and other routine maintenance.

My volvo has mind of her own, the past couple days Ive been fine at accelerating, and usually starts right up, (sometimes takes a couple tries before starting.) The only thing is that shes fine getting to point A, if I stop somewhere for 30 min or so, and I go to start her up again thats when she has the trouble (starting, accelerating, and stalling) Its like she needs 8 hours of break time before setting out again.
Whats could be the matter?