Both of the sensors are precision I think. Coolant sensor showed the correct resistance at respective temperatures. Ive got an IAC on the way because mine makes a terrible noise when i turn the Key on. I think I damaged it somehow when i cleaned it. I wasn't able to work on it today so I'll Re torque the manifold tomorrow. Also, I read that the EGR could cause some problems. If its stuck open it would act similar to a vacuum leak correct? How would I test it?

On a side note, after letting the engine cool i heard a really gnarly popping sound. Its much more predominant than your normal ticking accompanied with cool down and It sounded like someone hit a tin can with a wrench. I checked the freeze plugs and they seemed fine.. any other ideas or similar sounds?

 

TESTING THE EGR VALVE FOR 87-90 4.0 ENGINE

Valve Opening Test
1) With engine at normal operating temperature and at idle,
rapidly open and close throttle. Open throttle sufficiently to obtain
at least 1500 RPM. Movement should be noticed in EGR diaphragm.
2) If diaphragm does not move, probable causes are: faulty
vacuum signal to EGR, defective EGR diaphragm or defective
backpressure sensor diaphragm (if equipped), or leaks in vacuum lines
or connections.
Valve Closing Test
1) With engine at normal operating temperature and at idle,
manually depress EGR valve diaphragm. RPM should immediately drop,
indicating that EGR valve is not leaking and had been properly cutting
off exhaust gas flow at idle.
2) If there is no change in RPM and engine is idling
properly, exhaust gases are not reaching combustion chamber. Check for
plugged passage between EGR valve and intake manifold.
3) If engine idles poorly and RPM is not greatly affected by
manually moving diaphragm up, EGR valve is not closing off exhaust gas
flow. Check for carbon between pintle, leaking EGR valve gasket or bad
EGR valve.
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