86 F150 EFI problem
My father in law has an 86 F150 4X4 with 302 CID EFI and it bogs down an run rough intemitantly when the weather is warm ( 20 C +). It does not stall and he has removed the fuel cap, replaced high pressure fuel pump and replaced an various sensor MAP, throttle position etc. The only sensor not replaced is the O2 sensor ( he disconnected it and it make so difference on the performance). He had it checked for and OBII fault codes (none) Any advice why it runs poorly on occasion ?