I was sitting at traffic light and when i tried to go forward, my truck spuddered for a second like it was trying to go dead, after that and I got going, it ran ok.
What can cause truck to spudder from a dead stop and going forward?

I dont know if it is related but a few days ago, I had to take it to a shop because I had a coolant leak at the manifold gasket i guess it was, and they said some coolent went into where the oil is and it had to be changed. they pulled off some top parts of my engine and cleaned out an area where oil goes i guess.

Could it be that they missed a vacuum hose? spark plug/wire going bad? bad gas?

 

Can't be sure about the sputtering but it sounds like you had/have a lower intake manifold (LIM) gasket leak. These can cause catastrophic damage to these motors. Did the shop replace the LIM gasket? It is not small job. If they did, I guess it is possible that a vacuum line that they reinstalled might have fallen off causing the sputtering problem you describe.

The vacuum lines are easy enough to check. There are plenty of diagrams available through posts in this forum or elsewhere on the web.

 

I went to the shop and they had the top part of the motor off (it looks like a plastic air filter) and had what look like a pit exposed in the center of the engine, and he was drying it out, i guess it holds oil there and antifreeze had sprayed into it, he replaced the gasket there, it was about a foot long and 3 inches wide.
here is an image of the work area,



the gasket that got replaced was on the other side though. I dont know if he replaced both. oil looks good when i check it, they replaced the oil and oil filter.

 

Yep, your mechanic replaced the LIM gaskets for you and you had a leak into what is called the "lifter valley". The antifreeze leaks from any one of the four passageways at the very front or rear of the cylinder heads. The cylinder heads are what the gaskets lay on that have the passageways in your picture.

Also, your mechanic should have and very likely replaced both gaskets and likely more since the price of the gaskets is cheap compared to the labor to go back in and replace another one. Do you know if they used the Fel-Pro upgraded gaskets? These have a metal carrier for the seals that go around the passageways instead of the black plastic like in the original and in your picture.

BTW, the shaft in the middle is the balance shaft and the lifters (which ride on the surface of the cam-shaft) are below and to either side at the end of the skinny rods. Below all that and out of view is the cam shaft, then crank-shaft and then the oil-pan. Any oil used to lubricate anything in the vicinity of the lifter valley drains down through the lifter valley to the oil pan.

In the process of replacing these gaskets, a LOT of wires and vacuum hoses are removed that later have to be put back. It is possible something has fallen off.

It is worth taking your truck back to have the mechanic who did the job double check that everything that was reattached is still where it should be. He/she should not charge for doing such a check.

 

I looked at my engine and saw that there was a large hose loose from the back of that top plastic part that looks like an air filter, i plugged it back on and it seems to run better now. I added some barrs to my oil hoping to fix some oil leaks.

 

Yes, that hose would have caused a BAD vacuum leak and messed with how the engine would run. Glad it looks to have been an easy fix.

 

BTW, regarding the Barrs Leak stuff, I've heard many here not like the stuff but since you've already added it, be sure to report back with how it works.

 

Magic quick fixes are just that a quick fix that don't last, stop leak and such in the oil softens and swells seals and gaskets and such [good in theory] however after the swell they wear and detorate at a faster rate. I have however used Barrs leak silver in the radiator in my 83 Chevy diesel pickup as I was 100+ miles from home with a badly leaking radiator and no way to replace it - It's still holding after about ten years. KNOCK ON WOOD