i got a 1996 1500 360 and it runs rough after sitting a while till it warms up. once it hits normal temp it runs perfect but until it gets there it fights me i cant even drive it till it warms up the idle will surge up and then down and sometimes die. i am lost have done cao rotor plugs wires distributor cam and crank sensor plenum iac valve. the cat is gutted also

 

Check fuel pressure.

 

i put a new fuel pump in it to i forgot to tell you that

 

Gutted cat owner here and o2 sensor gave me hell..My guess it has something to do with your fuel as what hey you mentioned

 

What brand, and how long ago?

On the first startup of the day, will it run ok for a minute or two, and then starting doing strange things, or, does it do strange things right away?

 

Still check fuel pressure...new pump or not....

What brand pump? Any problems installing it?

What made you change it?

 

i forget the brand i had no trouble putting it in. it does it the first start up unless it cools down all the way. it just fights while it is trying to warm up

 

Still, I would verify fuel pressure at start up..... see what ya get.

What about O2 sensors? How old?