Chevrolet Repair: 94 gmc timing/ SBC 350, vacuum leaks, passanger side

Question
Hello I have a 1994 GMC K1500 pickup with a 5.7L V8. I just replaced my intake gasket and now it doesn't run quite right. The timing is not consistent it needs to be at 0 TDC. It floats around 0 but will go as far as 2 degrees before and after. Also with the timing light on it when you give it throttle it retards almost off the timing tab before it advances. I have a new cap, rotor plugs and wires and have checked the EGR, MAP sensor and TPS. So we finally advanced the timing enough so that I can drive it but there is still a decent stumble upon accelleration. I need some advice on where to go next or what I can check. Any help is appreciated. The only thing we did was replaced the intake gasket and now this! We also checked for vacuum leaks. Thanks in advance

Answer
just checking the past unanswered questions.  Sorry about the delay.  You asked another expert and they put your question in the 'pool'.  From there any of us can answer it.  If you still have the problem, I hope this helps.  If not, don't let this experience deter you from another question in the future.  Refer it to me...C J S.

Try using a vacuum guage.  That will tell you alot.  The floating is possibly causes by the irratic idle.  When you set the timing, did you put the truck in basic timing mode?  That is disconnecting an inline plug.  Usually Pink.  Can be found near distributor or along top of carpet inside truck passanger side floor.  Unplug this wire and a light will come on the dash.  Truck will still run and now you set the timing.  Dont unplug this wire while running.  Dont replug while running.  This could cause a spike in the computer.

Tell me what the vacuum guage says.  Try setting timing with basic timing mode.