Chevy caprice wont take the gas

my 1990 caprice 5.0L w/137000 miles. the problem is when you mash the throttle beyond 1/4 the engine bogs the farther you push the more boggy it gets. It does not die it just sounds like it is going to like it is running out of fuel. I has replaced the fuel filter the plugs the wires the cap and button. added fuel cleaner to the tank as well as heet to rid an water that might be in there. any thoughts??? I am unemployed so I have no way to hire a mechanic. any advice will be a heaven send. please and thank you…

Is the check engine light on? What type of injection, TBI or Multiport?

Sounds like a weak fuel pump. Fuel pressure should be 9-13 PSI, measure the pressure while accelerating.

I cleared the codes and it has not relit. it has the 2 injectors on top of the throttle body so I guess TBI?
How does one check the fuel pressure? Also is the fuel pump in the tank on my particular car?

You will need to disconnect the fuel line at one of the “quick connects” and install an inline fuel pressure guage. The fuel pump is in the tank.

Isn’t Heet a diesel additive?