What vehicle? C1500 regular-cab pickup? K2500 extended-cab? Suburban? What transmission?
Far as I know, ACDelco makes NOTHING.
They are a sales agency that buys-in their entire product line from outside suppliers; with a proclivity for Made-In-China production of many items.
ACDelco has at least three "lines" of product. They sell cheap aftermarket crap in their "discount" line, they sell better aftermarket crap in their mid-grade line, and they sell what they claim is original-equipment quality in their top-grade line...but "OEM quality" doesn't mean it was made by the same folks that made the part GM used on the assembly line.
WHY do you need an IAC? Have you actually done the diagnosis to prove the original valve is defective?
Absolutely. I disconnect a trans cooler tube, and route the fluid into a drain pan. Start the engine, let the trans pump the pan nearly-dry. Then you un-bolt the pan and it's not slobbering all over you as it comes off.
Clean the pan 'n' magnet (Some transmissions have a service bulletin for replacing the original magnet with TWO new/bigger/badder magnets) and replace the filter. I generally do not replace the seal in the trans that the filter plugs-into. Reinstall pan using the original gasket if it's the steel/rubber gasket style, otherwise use the gasket that comes with the filter.
Drop 5 quarts of trans fluid in the pan, open ten more and get 'em handy. Start the engine, dump fluid down the dipstick tube as fast as it will flow. Watch the fluid spraying into the drain pan. When the fluid spewing out of the cooler tube is bright, virgin red, shut off engine. Re-connect cooler tube, top off fluid as needed. You've just changed 95% of the fluid in the trans, instead of ~50%.
Absolutely. Use the correct fluid! Change front and rear differentials if 4WD.
Replace O2 Sensor. They get slow and weak with age. Some folks are upgrading to a 3-wire, heated sensor. But even a single wire, OEM-style sensor is better than an ancient sensor.
Flush brake fluid--I don't remember if a '90 has the iron RWAL with bleeder screw, or aluminum RWAL which needs a scan tool to properly bleed. Clean the fluid reservoir. Verify the three rubber brake hoses. Assure no leakage at the rear wheel cylinders especially. LOOK AT YOUR BRAKE CODE, which is likely JN/JB3, or JN/JB5. Might be JN/JB6 depending on vehicle. The "3" brakes are the weakest, crappiest brakes ever installed on a GMT400 vehicle. The "5" brakes are fine up front, but crappy in the rear.
Flush PS fluid, install PS filter in the return hose.
Flush coolant, including removing the block drain plug and knock sensor to drain the water jacket of the block. Consider all new rubber hoses while the coolant is drained. Look in the radiator, see if there's scale build-up. Make sure the fan clutch engages.
Transfer case lube (Buy extra Dex/Merc fluid when you get the fluid for the transmission.)
Grease all zerks in front suspension, check driveshaft for zerks.
Check air filter and air cleaner housing--does the heated air intake system still work?
Verify PCV system.
Check tire wear--showing signs of needing an alignment, or more-likely, parts replacement?
TBI distributors are known to have problems with the magnet on the mainshaft. Magnet cracks, ignition problems follow.
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EVERYTHING RUBBER is suspect. Belt (and tensioner), coolant hoses, vacuum hoses, grommets, control arm bushings, body bushings, tires, and so forth.
Verify everything safety-related: Brakes, steering, suspension. You're just about guaranteed to find heaps of worn-out suspension/steering components in particular the steering shaft rag-joint, but everything in general. Look at your rear-axle U-bolts. Commonly rusted beyond belief.
Connect a scan tool, verify EVERY sensor and computer output. Make sure the initial timing and electronic advance are correct/functional. Check fuel trims. See if there's any "codes".
I haven't verified that these part numbers are correct.
Again...have you tested these items to see if they actually need to be changed?
It is REAL EASY to CAUSE problems by replacing good OEM parts with crappy aftermarket parts.
