What sensors does an 89 gmc sierra 350 have that effects idol and fuel?

SOURCE: 2007 gmc sierra 2500 IAT sensor

Well, the IAT (Intake Air Temperature) sensor is located on the air intake duct between the filter and the throttle body (Assuming you have the 6L motor). The wires are easily visible at the plug that connects the sensor to the wiring harness. That's the easiest place to access them.

SOURCE: what transmission will fit in an 89 gmc sierra?

if it has a 4.3 liter motor a 86 to a 97 if it has a 350 motor a 81 to a 96 will work hope this helps

SOURCE: fuel pump fuse located on 1997 gmc sierra

The fuse is actually a Relay Switch and its located in the Fuse Relay Center on the driverside of the engine compartment. The Black Box is labled Fuse Relay Center, the diagram on the cap displays which Relay is the Fuel Pump relay...the Relay switch is usually $8-$15 depending on where you shop

SOURCE: 98 gmc sierra sputters and clacks when first accelerating

I wouldn't think it to be a fuel delivery problem anymore.If you could get someone to scan it while the problem occurs maybe you could see if your TPS is dropping out due to a faulty sensor or connector,also you could check for a blocked cat convertor by hooking up a vacuum gauge to the engine or a pressure gauge to the exhaust at 1500rpms should be no more than 1 to 1 1/2 pounds back pressure. Also you could check your magnetic pole piece that is under the rotor in your distributor they are known for the magnet cracking at the rivets.

SOURCE: where do i find a knock sensor a 1993 gmc sierra

Should be on the right side of the engine by the starter.Has a 1 wire connector.It does not go into the cooling system so you can just take it out without draining the coolant.Hope this helps.Good luck.