1996 Dodge RAM 1500 with the good old 360 5.9 magnum V8.

Ran perfectly the day before, then when I go to start it today it barely runs. Idles horribly and dies with any throttle.

Removed the air cleaner and tried running it spraying a bit of starter fluid. Idles out normally and runs fine with starting fluid. Changed IAC valve and runs a bit better, when I cover the IAC hole in the throttle body it runs a little better. Sufficient fuel pressure, sounds like a massive vacuum leak, huge air sound.

new fuel pump as of two months ago, good spark (I think).

thinking a plenum? It sounds like a huge vacuum leak but I’m not really sure. Battery is good. Alternator is good as well. Runs every time you turn the key but idles horribly around 300 rpm. Good oil pressure.

good readings from MAP and TPS. Map shows 15 psi without brakleen and idling horribly. 6 psi with fluid

 

I doubt the plenum gasket goes bad overnight to such a degree. You can check though if you feel vacuum at the dipstick hole. Is the truck parked outside in a rural area and rodents might have moved into the intake ? Or chewed through some hoses/wires ? Also try pinching off the brake booster hose.

Edit: Missed the part that it runs fine with starting fluid. That would make it more likely a fuel issue. The sucking sound might just be caused by the low RPM, does the sound change with starting fluid ?

 

What psi? And do you have it at key on no start? Any codes? A vac leak would make the idle go up so that doesn't sound like your problem.

 

The sucking sound goes away with starting fluid. It idles perfectly normally with starting fluid.

 

47 and yes. No codes

 

Might want to pull the throttle body off the intake and replace the throttle body gasket. Also, pull the IAC and thoroughly clean the well that the IAC piston seats in the throttle body to get all of the carbon removed. In addition, clean the throttle body, too. Disconnect the battery cables to reset the PCM, then re-install the throttle body and start up the truck to see if it runs better..

 

i had some thing simmler happen .the intake air temp censer was reading 40 deg when engine temp was 180 but it smalled of raw fuel at tail pipe

 

Points even more to fuel delivery. Could be an electrical issue causing only some injectors to work, or they don't open long enough. Or the "fuel sync" is out of whack causing the injectors to fire at the wrong time. Mark the distributor position (so you can adjust it to the original position) and turn it slightly in either direction. If that doesn't fix it it might need a new pickup in the distributor. Typically I'm not a fan of throwing parts at it but you probably don't have an advanced scan tool or an oscilloscope.

Completely out of left field idea: Any chance you somehow got water in the fuel ? Somebody messed with your truck ?

 

Hook it up to a scan tool to see what's going on. I'd like to see what some of the temp/sensor readings the pcm is seeing.