2000 Express runs rough after warm

I just bought this van...The van has had the cats removed before I bought it. All 02 sensors are there.
It runs good until it come up to temp. and still runs good until I come to a stop light. While holding the brake the motor trys to stumble and load up. As soon as I give it fuel it has a slight hesitation until the rpms come up and then runs good until I have to brake again.
It does have the check engine light on. I have yet ran a scanner on it. Will the removed cats cause this behavior?
Any help is greatly appreciated.

Suspect bad plastic, rubber, or seals on both the PCV & EGR system.
Consider doing a smoke test for vacuum leaks.

As said vacuum leaks and or egr valve.
But removed cats is a no no.
Creates many engine running problems
You need to get them back on.
Scan for codes and post back code no.
How many miles since last good AC delco parts tune up?

Thanks Daniel for the things to check.
MT I know the cats should be there but I bought the van and was unaware until I crawled under it checking other things out. I do not need a lesson in epa rules here but rather need to know if the missing cats cause erratic behavior like I stated after the engine warms up or not.

We can not say for sure on no cats causing your problem.
When you find your problem then you will know.

You are the one that came up with epa rules.

As I said no cats creates many problems like engine runing.

You need to get your codes and post back code no.
Have you checked the egr and for vcumn leaks?
How is the tune up end?

Yeah..If I knew what is wrong I would not be here.
I read for a day or so before I even posted and most of your replys were telling people to get the codes and report back...or do a Delco tune up or buy a AC fuel pump...you must own stock in the autoparts store industry.
I would rather you stay out of my threads. Go help someone else....
Anyone besides MT that has had what I am experiencing please post up with a little helpful advice.
When I get the codes and or a solution I will report back.

Sorry but you can not tell anyone not to answer your post.

Anyone can answer anybodys post as long as they follow forum rules.

But.
We with a attitude like yours you do not have to worry about me or many other people answering your post or trying to help you.
Have you read the forum rules about being nice and courteous?

:sarcasmsign:

Go have another beer under your shade tree. If all I get here is comments like yours I may as well spend the money and pay a real mechanic to fix it.

Now that sounds like a winner to me.
Good Luck

po104 codes low voltage on bank 2 sensor 1
no misfires codes...only runs rough after the temp comes up to over 170/
I also noticed it has alot of static noise coming from radio......seems worse the more it runs.