I have a 1986 Ranger XLT. My problem is that when it gets up to complete operating tempeture it boggs down to almost stalling upon acceleration. I've changed the following to no avail --Elec. Fuel pump,fuel filter,MAP sensor,TFI module,TPS sensor,Spark plugs,Distr cap and rotor,EGR valve. This is getting to be very frustrating. Also this truck has factory duel tanks with elec. switch on the dash.I've run the code reader on it and it gives me a code 77 for the KOER codes. Has anyone ever had this problem before and can you give me some helpful info as what else I can look at. Also I did a Fuel Pressure test.

what about the fuel presure regulator if you unhook the vacum line and gas comes out it might be bad i dont know if that would cause it but its somthing you could check

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88 Ranger

Im having the same problem did you ever figure it out?