i have a '93 f-150, 5.0L, 4x4, auto trans. there appears to be a problem with either it getting too much fuel or not enough air. this is what i have done to date: replaced the fuel filter, replaced the throttle position sensor, replaced the coil as well as distributor cap, rotor and plug wires. i have replaced the plugs twice though this does not seem to do any good. i will explain what i mean. with brand new plugs (gapped) installed, the truck will start and idle though it does not seem to be as smooth as it should. most recently, i did this process and started the truck and ran it for (5) minutes. i shut the truck off and it would not restart. there was an immediate strong odor of gasoline after cranking it for only (10-15) seconds. i removed these new plugs and they were fouled(soot)after running only (5) minutes. and also while it was running and reving the engine, smoke (looks to be blue) comes out of what appears to be a breather (approximately the size of the bottom of a pop can) which is hanging loose directly behind the intake. a metal line comes off of this breather and tees. (1)one goes down to the exhaust pipe and the other tee comes forward to the smog pump.

trying to check the codes with the self-check has not been very informative/helpful. these are: 118(ect). codes not listed in book are 629, 211 and 212. i also got a 1118 which does not make sense as it is a (4) digit code. we got these codes repeatedly.

i have not replaced the idle air control solenoid yet. i have taken it off, cleaned it thoroughly as well as the associated plunger. it seems to be working/moving (approx. 1/8") when cable is connected with the valve lying loose on the intake when the key is turned on (with the assistance of a helper). i just don't know how much it is supposed to move.
voltage at the IAC connector reads 11.56 volts though the book states it should be 10.5 volts.

the truck does not have a catalytic converter.

thanks for any help/info you can provide.

 

Sounds like you're not pulling or reading the codes correctly. Read this thread, especially the colored text AND post #9.

Nothing associated with the IAC should be "loose". Once an IAC becomes fouled enough to need cleaning, it's generally shot. If cleaning it helps, replace it. If not, you can try to keep using it.

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The broken check valve on the back of the engine is common, and DANGEROUS. The escaping exhaust can melt fuel lines &/or wiring.

. . .

You'll probably break the crossover pipe, so just plan on replacing it, too. It's much easier to work on them by removing the whole pipe - there are just 2 bolts: one on the back of each head, shown in that link.

 

Steve83,
I just wanted to say thank you, in all your replies, the diagrams you post are very helpful in your explainations.