All out of ideas

[84Longbed]

Aright where to start...
I have a 84 c10 (Scottsdale) 2wd. When I got it, the 305 and 700r had been ripped out and replaced with a 350/350 combo. Im unsure if the motor had been rebuilt, but I was told it had a mild cam in it, and it has a edelbrock performer intake. I threw Hooker headers on it a while back, and it ran a little better, but not much. About a week ago, the truck started stumbling whenever I encountered an incline, kind of like it was running out of gas. I replaced the plugs and distributor, and now instead of stumbling on hills, it does it at low RPMs, like when I accelerate after a turn. It comes and goes also. I tried to set the timing, but while watching the mark on the harmonic balancer, I could see it moving a little like it had slop in the timing chain. And while im on the subject, I think the motor may have the wrong timing tab on it as its a little towards the driver side of the balancer, but i got it to run best with the timing mark around the 12:00 position. How can I determine what year my engine is so I can make sure I have the correct timing tab, and is there another way to check for a stretched timing chain or if it has slipped a tooth other than watching it bounce around with the timing light? Thanks in advance for any help, I sure could use it.

[84Longbed]

I should probably add that the distributor I pulled off was toast, there were large pieces of debris all inside it. The plug wires have less than 500 miles on them, and the edelbrock 600 I just bought, but might not have tuned it properly. Also I just put the 89-91 grill on the front, and have yet to put the charcoal canister back on. Could my fuel pump be gone because of that?

[jonnydon]

hey ur idea is very good but i am not understand how u implement this idea

[juiceman650]

I just had a really good friend of mine that is a mechanic check my truck out today because while I was driving it, it seemed like I was "feathering" the accelerator and he said my fuel pump could be on its way out. I recently changed my spark plugs and checked to make sure I had the correct firing order. So it COULD be your pump. You could also check your firing order.
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[psuedopimp]

first find TDC of #1 piston, then mark your balancer at 0 on your timing tab. then it doesn't matter if your timing tab is the correct vintage or not. you just corrected it yourself. then check your timing.

check to make sure your vaccum advance didn't come unplugged and the hoses are good.