No power, hissing and melting parts in engine compartment

Hi. I am Shearie. I am a gal that likes to work on vehicles. I just learn as I go. No formal training in mechanics. I just bought a 2001 Tacoma with problems. The spark plugs were just changed and the oil changed for the first time in a year. I knew it had problems when I bought it, but I am hoping someone has the knowledge to point me in the right direction. It has no power. It is a 2.7 engine. I replaced the EGR vacuum modulator, cranked it and it ran great. Less than a 1/4 mile down the road it began hissing and lost power, spitting and sputtering. I didn't know if I would make it back home. I smelled strong odor of melted plastic. Opened the hood and the new Part I just put in (exact replica of old one) and put it just like the one I took out, was melted. The old was had the bottom blown out and the bottom hose missing. What could cause such a back up of pressure and heat to do this? Now I am back to square one. Any one out there ever had this problem? Also the check engine light is on.
Thank you for any advice you may have.

 

You should probably check the codes first.

 

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