misfire one cyl. 1 1999 jimmy vortec
 

after hard starts, gas smell under hood and #1 misfiring after tune up i replaced the spider with a salvage part. then it misfired on #4. took it back, got another spider. it then ran worse than ever misfiring on #5 so i took the #1 noid out of that spider replaced it in my original. then it was misfiring on #4.on a whim i swapped the #2 & 4 plugs to see if the miss would move to #2. it moved back to #1 I'm kinda lost. fuel pressure is good. it's got a month old distributor, new cap/rotor & plugs. how can i misfire move so much. thinking of buying a new spider but after reading other posts I'm not sure what to do next. also replaced vacuum hoses

Did you use AC Delco platinum plugs & AC Delco cap & rotor? What about your wires? Were your Poppets leaking? Is that wy you changed them. You need to do a fuel pressure test & a leak down test.

i wasn't aware of the need for ac delco parts before i bought them. this is my first vortec. the misfire has moved from 1 to 4 to 5, now back to 1. that tells me the plugs,cap, rotor seen to work , i found little fuel when i changed the spider. having to start with ether more. i did pressure &leakdown and had good pressure

Try changing out the fuel pressure regulater its the little down spout thing on the back of the spider assembly,It is held on by a clip and there is a rubber O-ring inside. And to check the plug wires you can swap 3-2, 1-4, 6-5, those are the closest in size to one another. And trust me spend the extra money one the A/C delco/Delfi parts they are right about that!

that's what I'm going to do. i was thinking the regulator was something i haven't tried, other than the 2 salvage spiders having a different reg. . i've had to use ether to start it the last couple times I've tried. could it be a timing chain problem was another thought

Sure sounds like low fuel pressure to me ;) The leakdown test will confirm or deny a regulator problem too.
Key ON, engine OFF, fuel pump running: Fuel pressure must be 60psi to 66psi and must remain above 55psi for at least 10 minutes after the pump shuts off? Post your results.

Timing chain problems on these engines are not an issue, don't waste your time or money there.