i have a 1992 ram 150 4x2 with a 318. Its a little hard to start at times and has a real rough idle to the point of dying after being driven for a while. Its the worst after getting off the freeway and it seems that if i put it in Neutral when i'm stopped it doesnt bog down as much but when i put it back in drive i have to go quick or it will die. I have changed the seal inside the intake manifold, the o2 sensor, rebuilt the injectors, checked for vacume leaks and i am stumped. Any help would be greatly appreciated.

 

Have you checked the EGR system?

 

have you done a tune-up, spark plugs, wires, cap, rotor.

 

I have the exact same problem with my 90 W150. I haven't done it yet so i cant say if it will cure it or not but.... From what I've read it sounds like it might be a problem with the MAP sensor, and it may need replacing.

I am going to try that eventually but if you do it soon please let me know if it works. Thanks!

 

mine is doing the same exact thing on my 98 dodge 1500 with the 5.9, Ive tried everything but the map sensor and the pcm, but im also getting codes 132 and 138? let me know if you figure it out, Im about out of hair to pull!!!

 

a 92? been a while and if I remember- a throttle body set up?

let us know if the CEL is on and also if it does the bulb check on start up?
vehicle is stock?
trying to answer you without the info
3 things come to mind - problem with IAC or TCC would both fit the description,
as well as the mentioned EGR valve...

 

there is a big difference between a 90 and a 92.

 

ive got a similar issue on my 91, only it does not have a rough idle. In addition to stalling after being on the highway, when i hit the gas from a full stop it bogs down like something is resisting it turnind and then "POP" a misfire or backfire out the carb and it goes along fine. I havent replaced all the possible sources of this problem, (like MAP, TPS/crankshaft position sensor for the 92, pickup coil, a vacuum leak, EGR valve, O2 sensor, and some others) but i did run tests to rule them out. everything seemed ok when i applied vacuum or checked with a multi meter.

the one last thing it could be is a clogged cat.

 

it is a throttle body set up, stock, no check engine light. but whats the light bulb test?

 

does it come on when you start the truck just to show the bulb works