Nissan Repair: 87 Hardbody Running Problems, fuel pressure gauge, air control valve

Question
I have 2 1987 Nissan Trucks Z24 engines, both great trucks but both are having running issues

The first one starts fines runs good on high idle but once it comes off high idle the idle surges between 400-1200 RPM and this never changes, there is no problems while driving just at idle

The second truck runs great all the time but once it warms up (and it seems to be temperature related as well) the truck has great difficulty starting almost acting as though it is flooded as I have to put my foot on the floor to get going and then feather it back to a good idle

Any suggestions would be greatly appreciated thanks

Answer
Dan,

On the first truck replace the idle air control valve.  That should resolve the idle issue.

Sounds like leaky injectors.  I would look at doing a leakdown test on the fuel system.  That is, get a fuel pressure gauge and attached it to the pressure port.  Now, start the truck and turn it off.  If the fuel pressure leaks back to zero you have an injector or two leaking.