95 astro stalls......

95 astro 2wd. the van runs like a champ, until it warms up. when i drive it a few miles, the idle drops and it runs like garbage, sometimes stalls. yet after i hit the gas it runs fine, even under load. it idles fine for about 15 seconds then craps out again. ive read all i can here about stall problems, yet nothing ive read fixes it. now the funny thing. it only happened after i took out the cat because the insides were rattling and driving my dad nuts.

fresh tune up, cleaned the iac, still same result. no codes either.

it runs perfect until i stop idle for 20 secs or so then craps out, but if i hit the gas under load or not, it takes off smooth and powerful.

anyone ever hear of lacking back pressure in the exhaust causing idling probs?

It's more than likely a fuel delivery problem. The spider is probably failing, or rather the fuel lines that feed the fuel pressure regulator portion of the spider.