Advice needed
 

02 blazer 4.3 4wd

Ive got issues with Starting the engine. At times I will turn it on, it starts right up but doesn't stay going. I can tell then I step on the gas n it'll still run but as soon as it goes to an idle it'll putter out. I wait a could seconds try again n usually the second or third time it'll go. Now I just replaced the alternator and the battery about 4 weeks ago. And it's been doing this since. Did change the neg terminal bolt when i replaced battery as it was rusted. Last Friday I took a look at the terminals n decided to just change the pos Too as I had the bolt anyways. Did notice it was wet inside but thinking it was from anticorrosion ring I had on it. But wiped it out n tightened it back up. Truck still has the failed turn overs. I know the battery guage twitches on dash sometimes but had autozone test that and the alternator n they both were good. Also at times it seems like it may be starting hard. Like the turn over isn't smooth. It seems loud and somewhat sudden. Just isn't right.

Also have been having problems with the oil guage fluctuating when driving n stopping. Don't think they are related but I could be wrong. It doesn't go down far enough where the light goes on but I know it isn't right either. That itself started happening after I took it in to get the fuel pump done. Which was quite a while ago. Don't know if the place I took it to jacked with my truck or what. But I had no oil on the dip stick n i know it wasn't that way before as I've always got to be on top of it cuz my oil always seems to dissappear. N when I went to change it that time, my oil pan bolt was on super tight. No kidding. Since then I've done all my own work. N have been keeping up with oil changes. I know i have a couple small leaks on my head gasket. But I don't think that could be enough to make that guage bounce back n forth like that.

Any advice would be greatly appreciated

Does the engine not start or starter not crank(no start vs no crank)? Makes a difference with what troubleshooting steps you take.

How is your cap and rotor? Plug wires? Plugs? Coil?

As for the oil, check the wire connection at the oil pressure sensor.

Try a leakdown test to see if something in your fuel system is amiss. Connecting a vacuum gauge can give you a visual representation of what your engine is doing. Local auto parts store can usually rent those, new fuel filter if it's been a while.

There is good leakdown sticky here in this forum to help guide you if needed.

Still a mess
 

So I know it needs a new fuel filter. The one I have on I can't get off. Tried 2 separate times. Rusted on. So it could more than likely be just that. Just strange how the battery guage drops when that all happens. N it turns over most the time. But there's times when it doesn't stay on like it's weak. As I said in original post. I step on the gas n then it seems as it will go but as soon as i let off gas its back to running like its about to die. If i whip it in reverse or drive itll die. No check engine light just battery liget on dash shows. Sometimes it'll crank almost start but I can tell is not going to be a good one so I turn the key back wait a couple seconds then try again.
Changed plugs n coil 2 summers ago, so they should be good yet.
Gotta alot of issues with this trucka. Oil n coolant dissappears also. Which would explain the oil guage fluctuating. Upper intake manifold gasket needs to be replaced. That'll be a chore.
don't know if I should keep on going fixing it or just let it go. It's a bummer. One thing after another