98 GM 5.7 slugish @ 70

If you have that spider fuel system, I always check that first. That system is noted for problems. Use a gage and check proper fuel pressure, 60--66 psi. After you get it started, It should run with less pressure.
How long since over-all tune-up? Any applicable trouble codes?

Chevrolet Suburban Questions - 4 wheel drive does not ...

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CarGurus4 wheel drive does not work - When I put the Sub in 4 wheel drive, low of high, ...Asked by Robert_Holland_073 Dec 17, 2009 at 04:06 AM about the 1994 Chevrolet Suburban K1500 4WD ... it can seize up and then the trans case may ingage but the hubs won't be locked in so it ... 1999 Chevrolet Suburban K2500 LT 4WD.

Chevrolet Tahoe Suburban 4 Wheel Drive Indicator Lights - Car ...

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Oct 2, 2007 - 31 posts - ‎19 authors
My 1999 Tahoe (odo reading 137,400 miles) won't go into 4 wheel drive. .... I have a 98 suburban 1500 4x4 LT 5.7 L with 165,000 miles ... I recall once forgetting todisengage 4WD and I could feel a terrific binding when I ...
Step by Step Troubleshooting 4wd 4x4 88-98 Chevy GMC ...? 21:32https://www.youtube.com/watch?v=Su9Dkrfd_ZgJan 20, 2014 - Uploaded by rwdellingStep by Step Troubleshooting 4wd 4x4 88-98 Chevy GMC Truck. rwdelling .... Mine is acting like it is NOT pulling with the fronts,won't engage. ... Have you ever adjusted or the shift cable on your 1500 Chevy ... GM 246 transfer case, 2000 Chev Suburban- Duration: 20:09. by spelunkerd 286,045 views.GM Troubleshooting Part 13 - 4WD vacuum actuator & cable ...? 5:11https://www.youtube.com/watch?v=CbEF6PyJdU0Feb 3, 2011 - Uploaded by mr diyguy123I tacked on this video about the 4wd sys. ... I have a 1994 ChevyS10 ... My S10 won't let you go to 4 LO when your in gear. ... the front end to keep them disengaged. when you put it in 4wd, the vacuum actuator pushes a gear ...

There's a routing diagram sticker under the hood. Look for it on the radiator support , the front shock tower or on the hood itself.
type this on google and see what you get...gmc k1500 serpentine belt routing diagram

Have to service these a lot it's the MAP sensor ( manifold absolute pressure sensor ) this should fixya.

That is usually the fuel pump in the tank you to check the fuel pump pressure in all conditions as these are sensitiveJohnny

If it is running bad enough to be backfiring, the Check Engine light should be on. I would start with scanning the engine computer for fault codes.

If at idle it doesn't get cold but at highway speed it does, the system could be low on charge, or the compressor may be worn and isn't generating enough pressure in the a/c high side lines, or the orifice tube is blown out.

Sounds to me like either your pressure regulator is bad or you have a loose fitting somewhere in the fuel line from the fuel pump to the engine. When you turn your key to the on position, you should hear the whine of the fuel pump until it builds pressure. When you shut the truck off the pressure regulator should retain the pressure for a certain amount of time but if it don't close then air is allowed into the fuel line and the fuel drains down to fuel line away from the engine. Next time you try and start the truck after it has sat for a while try turning the key on until you hear the fuel pump whine shut off, then repeat it 3-5 times and then try to start it. Basically that is running the pump enough to get the fuel back up to the injectors. Check for loose fittings in the fuel line, or cracks in the fuel line and if all that is fine then replace the regulator.

Hope that helps

GM is known for faulty ignition switch on that model.

i would try a fuel filter first. the fuel gauge going crazy is most likely the sender they go bad and eventually stop working. the bummer is you have to replace the fuel module. these aftermarket are about 200 bucks. the module comes with the pump and sender which is the next part you want to look at. gm has some issues with the harness to the fuel pump externaly. it actualy will melt and start to lose conection. i would check this by visualy inspecting the plug on top of the tank. unplug it and take a look. if it is at all disscolored replace the pump (module). the new pump comes with a replacement harness (make sure its in the box)hope this helps and good luck