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1993 toyota pickup
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Discussion Starter #1
I have a 93 pickup i4 and when i start it, at first it idles fine but after a few moments the rpms begin to drop almost like it's going to bog out but then it picks up again. It keeps doing that until i rev it for about five minutes then it gets slower and eventually goes back to normal. Why does it do that and how can I fix it?
 

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First I'd clean the throttle body and set the idle speed to 750 rpm and see how it does. See these threads:
http://www.toyotanation.com/forum/showthread.php?t=292224
http://www.toyotanation.com/forum/showthread.php?p=2733671#post2733671

If you haven't done a tune-up lately, replace the plugs with the recommended Densos, and the cap, rotor, air filter, plug wires if necessary (Denso's are best) and set the timing.

If O2 sensor has more than 90k miles, replace it with a direct-fit Denso (or NGK (NTK) if $$ is tight) sparkplugs.com has cheap prices for these parts.

If valves haven't been adjusted in a while, do that, and check your timing chain guides while you're at it. Search forum for instructions and lash specs (factory manual specs are not recommended).

If still problems, check the tps, vafm & ect - search this forum, there's a lot of info on each. Drop a bottle of Red Line SI-1 Complete Fuel System Cleaner in the tank (only product that still has a good concentration of the best injector cleaning chem, polyether amine (PEA)). It may take a couple treatments to get the injectors clean. Check for vacuum leaks and cracks in the air hose. Check the EGR for proper operation. Check the signal rotor clearances and signal generating coil in the distributor.

You may want to clean carbon and gunk out of the intake, valves and cylinders with a Seafoam treatment; if so you'll want to do that before replacing any tune-up parts. See the second thread link above.
 
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