Hello HIKCM,
Using a Block off plate where the EGR was mounted to the intake manifold does several things:
1. Allows You as an owner of a vehicle that is 20+ years old to simplify and eliminate a major failure-prone part of your emissions system without any negative effects such as a possible vacuum leak from a thinner, home-made piece of metal plate instead of this one that is very thick aluminum with a coat of Silicone on the side that touches the intake manifold.
2. Once You remove the EGR system, You can also eliminate the hot exhaust tube coming from Your manifold and use a plug or plugs to cap the hole, along with the removal and re-route of all of the Vacuum hoses that are hooked to the EGR solenoid assembly and Fresh air injection unit.
SIMPLER IS BETTER IN OLDER VEHICLES.
We all know and love Toyotas for their well-founded reliability, and eliminating what is likely a poorly-functioning, worn-out emissions system will do nothing but improve conditions for the engine and extend it's life.
3. If You truly want to do the best thing possible for your truck for emissions reasons, remove the EGR system and air injection pump and replace the old, wore-out catalytic converters for new, high flowing units that work well. Install new O2 sensors and do a tune up. Voila! Better than new or almost so....