Engine help!

ok i got a 92 FI b2200 not to long ago and when i first got it the engine would barely run for more then 5 mins. I was told it might be the fuel pump from the previous owner cause he had put in a used one from a junkyard. First it was over heating so i put in a new thermostat and did a radiator flush and that seemed to stop the over heating. But it still had a problem where it would run normally then out of no where it would begin to idle really fast and if you press the gas it will bog out, lose power and almost die. I also hear it back fire sometimes when i hold the gas down when its doin this. So i replaced the fuel filter, cleaned out the screen that is attached to the fuel pump in the tank and did a fuel pressure test which gave me a normal reading. This helped the problem a little bit but didnt cure it. I notice that there is a bit of water dripping from the tail pipe but not blowing large amounts of white smoke or anything. So i thought maybe a cracked head gasket but there was no oil in the coolant or coolant in the oil. So my only guess is that it is a very small crack in the head gasket or perhaps a intake leak somewhere? Its very hard to trouble shoot cause it seems to just happen out of nowhere, one day it will drive fine the other all crappy again! Any help is appreciated!

to me it sounds like a vacuum leak. the water coming out the tailpipe can be a totally normal thing.
when you say it does it after it warms up a little, makes me think something about the choke, and still a vacuum leak.

Just to FYI ya, the water from the tailpipe means your cat-converter is working!

dam so after a week or two of runnin really well the problem came back again after sitting for a week. Engine starts but immediately starts to idle really fast and bogs out when i press the gas. I was thinkin it might be the fuel pressure regulator creating too high of a pressure and giving the engine too much gas. In my haynes manuel to test the fuel pressure regulator it said to block the return line of the fuel regulator and then test the fuel pressure and it should be between 27-36psi. I did this and i got 60psi...but wouldnt blocking the return line create a higher pressure?

Ya blocking the return will cause higher pressure as it has no where to go but out the injectors. You may have a IAC problem or computer staying in cold start mode closed loop

To me, the problem sounds like a vacuum leak- with an efi truck- it uses a mass air flow sensor. If a vacuum leak occurs, the idle will increase because of the added air, and throttle response could be limited because unmetered air is entering the engine, and the mass air flow doesn't know about the air entering the engine from somewhere else. Because of this, the fuel injector duration is not correct and the truck will not adjust fuel and spark correctly, thus no throttle response and backfiring.

A leak that occurs suddenly and cuases the idle to increase should be obvious to find. I'd check the egr valve- make sure it isn't bypassing air through it- check the diaphram, is it crunchy? If it is- it's bad. Also check the IAC valve, when the truck idle increases- pull wire to the IAC valve, does it change?

ok so its been raining for the past week and i noticed the passenger side carpet was kinda wet. Turns out water was driping from the windsheild and down onto the computer a bit. Not sure if it got inside the computer at all but pulled the computer and let everything dry and tried to start but now it doesnt start at all.....pulled the spark plugs and it wasnt getting any spark. I checked the coil and that wasnt sparking either so i measured the primary and seconday coil resistance and that checked out so im pretty sure its not the coil. Even if the computer is toast wouldnt i still get some sparks? oh and anyone know where the egr valve is on the efi engines?

opps I forgot a b2200 F I truck doesn't have an egr valve!