i have a 94 5.7 4x4. the temp outside has started to drop into the 30's and ive been having issues in the morning where it tries to die in the low to mid rpm range while accelerating and it did die once but started right back up. it runs normal during the afternoon though. could it just be that it needs more time to warm up or the start of another problem? its had a tune up a few months ago. also i recently noticed a little whining/hissing sound which i believe is some pulley bearings starting to go.

 

Check for vacuum leaks.. might check iacv./idle air control valve.

 

check the coolant temp senser resistance when its cold to see if they match the book values,does it still have that heated air intake system(thermac,efe)hooked up maybe thats not working properly or the source of the vacuum leak

 

I dont know, I think you have a bad battery. Or bad battery connections.

 

If it's not slow cranking when it is cold, I'd not think battery. Could just need a $5 can of MAF cleaner. The Mass Air Flow sensor tells the ecm, or pcm how much air flow is going into the engine, so it can determine fuel.

 

Well even if battery was dead would still run off of alternator?
94 5.7 have no maf sensor.

 

well good news and worse news. it hasnt stalled again but today my tensioner pulley seized up. seems like a very simple fix. i'll keep all the advice in mind if the problem occurs again. i have good battery connections and a solid ground. seems more like a air/fuel mix ratio issue

 

today i noticed a pretty loud hissing sound from the brake booster inside the cab. seems like a bad seal and i plan to change the booster out soon...could the loss in vacuum seem to be enough to make it bog down during hard acceleration? might be able to get two birds with one stone on this one...

 

Yes..