a heat stressed part?

ok. i have now tracked down and eliminated the 400 code (found the problem on the vacumm/vapor rail mounted on the firewall), but the shut down still continues. the computer shows no codes now, but when the engine gets warm or hot, it will start sputtering and gasping for gas. the fuel pump is working, so i have wipe that one out. whatever it is, it is getting heat stressed and causing this. i need to know the following: is there a way to check the fuel injector without just looking down the throttle body. the part is just too expensive to just replace at a whim. also, what is a tbi injector insulator? i don't find it listed in the manual. is there anything i am missing here? how about the fuel shutdown solenoid? where is this piece at and could it be causing the problem? i am just about at the point of replacing all parts in the fuel delivery system. :naughty: