1993 454
Truck has occasionally had a slight hesitation for a while. I just figured since it sits for long periods of time that it may have water in the filter/bad gas, and it wasnt problemsome, so I never really looked into it. In March I drove it approx. 125 miles (after sitting for about 9 months with just periodic start ups). Put gas in, drove 60 miles to a show. Didnt run totally great (bogged down), had to feather throttle to try and get it to "clear out". The next day drove it back, ran a little better but still not great....That was mid march. Parked it in garage, been sitting since (started it up twice to run for about 5 mins). Always smells like it runs rich (again, figured it was because it sat so long) I replaced the plugs and wires about a year and half ago (but really only about 300 miles ago)

Flash Forward to last night. Start it up, pull it out if the garage, let it idle for a while everythings fine. Go to take off and its running like crap. Sputtering, hesitating. Again, feather the throttle (really only about 30%) to get it to run semi-smooth. Decide to keep going onto a cruise night (about 20 miles away) Soon as we get there its really running rough. Get off freeway, and at both stoplights it tries to die. Make it to cruise night. Start it up later, still running crappy, go to leave and it dies. Will only start up for about 5 seconds. Cant feather it or anything to keep it running. Look in fuel cell, and fuel looks cloudy. I checked it before I left the house, and checked it again at the cruise night... looked normal.

So now Im thinking, did i accidentally put diesel in it? Im completely denying it... No smoke, and i dont think id do that. Drained all the gas out (wasnt diesel) but there was kind of a jelly substance at the bottom of the cell. Put fresh gas in, doesnt fix it. Run Diagnostic/check engine light on (pre obd so it doesnt tell u much to begin with). Says Bad MAP sensor. Replace that, still no good, but check engine light goes off. All diagnostics good. Pull fuel filter off (was already brand new), blow it out backwards into cup. Kinda weird. a few small bubbles (resembles putting vegetable oil in water). Put new filter on, still didnt fix it. By this time it has been running long enough that all the old fuel has cleared out.

Couple odd things. Right now its sitting at a slight incline (nose down). idles decent, but as soon as we go to pull it down into the street it dies when it gets level.... No its not the pickup, cuz that is at the rear of the tank
Also, it seems to idle better with the map sensor unplugged (computer going into fail safe mode?)
Have intake off and you can clearly see the injectors spraying fuel... Fuel pump is working, but maybe is it not working at right pressure?

Any ideas?

What injection type is on the motor? TBI is assume by the year.

Does it have catalytic convertors on it? Mine had real similar symptoms last summer, ended up being a plugged convertor. The honeycomb looking stuff inside had broke and separated, which in turn didn't flow to good, then melted and eventually plugged up the exit side of the cat. I just pulled mine and put straight pipe in their place and seems to run good now.

Lock....yes

no, no cats

Mine did about the same thing a few years back and it was the secondary injector on the TBI. You can take them out and clean them but they are fairly cheap to buy and I just replaced both at the same time.

anyone else wanna put in on this?

Have you checked the O2 sensor?

We were gonna test it to see if it was running rich or running lean... but the O2 sensor doesnt kick on until the exhaust reaches 600 degrees.... which its not gonna do right now

I ordered a fuel pump... hopefully put it in Saturday to see if that fixes it... Gotta start somewhere...