88 chevy c1500 dies when I put it in gear

checked the fuel pump and put in a new fuel filter. now it will start but it stays in a faster idle even after it has warmed up and been running for
20 minuites. when i give it a lot of gas or put it in gear it quits and takes a little effort to get started againbut will go back into a fast idle until i try anything again.
hopingsome one out there knows more on how to fix this than me. thanks
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.