Well after reading a bunch of these, i feel a little better than i am not the only one having the same problem too. I have a 87 F-150 with 89 460 EFI. I rebuilt the the whole thing and it's making me mad. I have put everything new in it besides Coolant temp sensor and fuel pressure regulator. mine runs great for the first few miles as well. loses power and then when shut off won't start, it will just sit there hardly idle or die. if you give it more throttle it dies or do nothing. no check engine light has come on either. unhooked the tps and motor shuts off. so my last option is it's prolly the fuel pressure regulator. That's what i am going to try. all other trucks i have seen have bad O2 sensors never really ran that bad. heck my old build 302 i had in it before didn't even have one and i put a block off plate on the egr and ran just fine.