Why does your 1987 Astro go full throttle when the engine is started?
Your 1987 Astro might go full throttle when the engine is started because the throttle is sticking. This could also be a problem with the starter or the ignition hanging during the start.
Remove the air filter assembly, on the right side of the engine adjacent and below the the accelerator linkages, the throttle body is located. At the rear of the throttle body is a set screw which establishes how much air is allowed to flow at zero throttle. Unfortunately if the throttle body is leaky replacement is necessary. Check the timing -- and the fuel mixture as well. Either one can result in high idle RPMs.
I think in 1987 the fuel pump was still located on the front of the engine block next to the water pump and was actually driven by the cam gear. Follow the fuel line from the throttle body to see if it goes to a small space ship looking part on the front of the engine. If it is not there it is probably an electric pump located on the frame next to the main…
The location of the EGR valve on a 1987 to 1989 Chevy Celebrity depends on which engine the car has. If the car has the 2.8L V6 the EGR valve mounts to the plenum near the throttle body. If the car has the 2.5L 4 cylinder engine the EGR valve mounts in the center of the intake manifold near the valve cover.