95 1500 350 auto hesitates and has no power when warm

I just bought a 95 chevy ext cab z71 with 5.7l 350 TBI. I runs great when cold...sometimes cranks a long time to get started but then runs great until it warms up. Then is sometimes dies when you put it in gear or at stop lights. When your on the hwy and try to accl its like it has no power. Past a point then it will take off and go. It's like there a spot just above cruising speed that it won't "take gas" so to speak. It also seems to be running rich because it smells extra fumey like its burning to much gas. I check the vac lines for leaks and can't find any. I also took off the egr valve and IAC and cleaned them good with carb cleaner. It has 237,000 miles on it so I guess I should be glad it runs at all but I sure would like to find a cheap way to fix it so it runs correctly. I put seafoam in the gas and have ran a tank out with no inprovment. I also have replaced the Fuel Filter and checked the plugs and wires. They seem to be near new on it. Any ideas would be greatly app. I am handy with cars and have most tools I need. I just don't know where to start on a problem like this. The engine sounds good and does not smoke. I may have had a rebuild by now or different eng put in it. I don't know.

no codes?
checking the ect and iat and fuel pressure would be a good starting place.

Check your fuel pressure regulator as well as fuel pressure.

yup it sounds more like the fuel pressure regulator if not try to take your MAP sensor to get check or tested at your local auto parts I think it has to do something with it my buddy that's a mechanic told me that when the sensor fails the truck will get rich on fuel.