Ford Repair: 86 f 150 Fuel Delivery Problem??, coolant temp, firewall black

Question
I have an 86 F150, Auto 302,FI,(not original motor). The other day I was driving along and the truck started to sputter and died out. The truck will restart all day long but will not stay running unless you keep your foot on the gas. I ended up driving home like this, revving up at stops. There was obviously a strong gas smell and a black/blue smoke coming from the exhaust. A couple months back I replaced the coil and advanced the timing just a little. The truck had been running well up until this point. I have checked the fuel pressure...35 pounds but starts losing pressure at about 1 minute.(not sure if thats normal) I pulled the vacuum on the regulator, no fuel present.I changed the plugs to see what they looked like and it needed to be done anyways. They were pretty carboned up. The only other thing I noticed is that there is a return? line from the exhaust running up near the firewall, T's off and runs to the old air pump?? I assume the air pump is operated by the ac in front of it which has never had a belt on it since i have owned it, so i assume the air pump does not work.Not sure where the other one goes.
Here are some of the things I have been told by various people that could be wrong (none of which are mechanics!)
Leaky injector(s)
Plugged muffler/converter
The return line that broke is the problem.
Any ideas are greatly appreciated!!!
Thanks in advance,
Shawn

Answer
Shawn,

It sounds to me that your truck is running rich and getting too much fuel. The two main causes are your map sensor and a coolant temp sensor.  

First, the map sensor is mounted on the passenger side of the firewall (black with a vacuum line and 3 wire plug).  Make sure the vacuum line is connected and not pinched. Second try unplugging the map sensor and start the truck. The computer will substitue know value in its place and probably kick the ck eng light on. If it runs good then replace the map sensor.

If that doesn't work check your coolant temp sensor. It is a 2 wire round connector mounted in coolant flow path. I think it is in the lower intake on that.  Back probe the green wire with a volt meter. Turn the key on, cold engine should be around 2.5volts. Start the engine and let it warm up. The voltage should go down as it warms up. Fully warm should be around .5volts.

Good Luck!!