Ok guys, need a little help on this one as i've never encountered an issue like this before. I've searched and found some similar problems other people have had, but nothing with quite the same symptoms....anyways when i'm going up a hill or holding the needle steady at between 1700-2100 rpm, my truck will sputter or suddenly lose power and then gain it again. It happens so fast that it almost feels like you hit a bump in the road or something. It's definitely an engine sputter though and i'm pretty stumped.

Also, on the way from work to my gym, it had been sputtering like that pretty regularly for about 15 mins (i was baby-ing it to try to make it home) when suddenly the battery voltage gauge dropped all the way down to 8 (as low as it will go).

Here's what I have done within the last 2K miles:

Plenum repair (hughes airgap)
SCT 93 octane tune, 180 degree thermostat
Autolite plugs, autolite wires, bwd select cap and rotor, cleaned IAC

Within the last 10K:

New fuel pump assembly (airtex - i know, ugh)
50 mm throttle body
Cat back exhaust

Still stock:
O2 sensors, cat, alternator, distributor

I guess the million dollar question is, does this sound like something as simple as a bad alternator or am I looking at possibly a bad voltage reg. in the PCM? Or a short in the battery? Or a defective fuel pump? I tested the battery and alt. at advance and they both checked out ok... The sputtering is still pretty intermittent and it ran fine from the gym to my house (15 mins.) After I did all that plenum work and tune up, it ran and idled perfectly and still idles perfectly even with this sputtering problem at low rpms. HELP!

 

Disconnect the front O2 sensor, take it for a drive, see if the symptoms go away.

 

Yup that's my plan for tomorrow...it didn't do it at all on the way to work this morning (outdoor temp around 50-55) but it did start to sputter and cough on my way to and from lunch (outdoor temp around 82)...heat seems to be playing a role because I didn't notice anything on my way to work yesterday but it was sputtering pretty regularly on the way home in the afternoon.

 

if the 02 dont fix it, id be checking the ground on the battery man, when it dropped sounds like you lost ur battery power and was runnin on just the alternator, i have done this before in a car, had a dead cell in the battery. you gotta goto a place that can test for a deadcell, walmart can, autozone couldnt. a normal test it will still pass because the charge can still pass thru it but that dead cell wont hold it and it will still be bad. just a thought.

 

I had thought about that too, in my first post I mentioned a possible short in the battery...I have another ram at my house with a good battery in it so I may try swapping them and see what I get. I'm fairly certain it's an electrical issue because the voltage gauge was dropping and rising again during my drive at lunch while it was sputtering.

 

the dropping and rising is prob from the alternator doin its job. let me know what happens when you swap the battery, also make sure the connections are all good from the battery to the fuse box and the grounds to the frame and firewall

 

Just to bookend this post, the problem ended up being the alternator after all...guess my first hunch was right. On friday, the darn thing was acting up again and was sputtering until the battery gauge dropped down to nothing...got to the gym, started it again and the voltage gauge never even reached 10 or 11. Got to my girlfriend's house, replaced the alternator, problem gone. The engine is a lot quieter now too lol, the bearing on the alternator was horrible. I had bought it that way so I never knew the difference I guess. Thanks for the responses guys.