Hello, I have a 1995 Ford F-150 Eddie Baur 4x4 302CI 5.0L EFI V8.

The vehicle finally runs but seems a bit sluggish. My neighbor, a mechanic, says I need a whole new engine, but I don't believe him just yet.
The codes it was throwing were as follows:

Key On Engine Off:
-121 [No Longer Appears since June] Closed Throttle Voltage Higher/Lower Than Expected
-565 [Last Appeared Today] Canister Purge Solenoid Circuit Fault

Continuous Codes:
-172 HEGO (HO2S) Sensor Fault/Lean
-332 Insufficient EGR Flow Detected

I have replaced the fuel pump, fuel injectors, fuel filter, spark plugs, spark plug wires/boots, fluids, vacuum hoses, oil pressure sending unit, VSS, TPS, all fuses, terminal wires, and ground straps, etc.
I also cleaned out and replaced the gaskets on the intake and upper manifold while I was in there replacing the fuel injectors.
It runs a lot better than when I first got it, but it still won't go over 35 and runs through coolant. There's apparent leaks and stuff, but the oil level remained full.
When I replaced some of the vacuum lines, especially for the AC flapper (Max AC Used to blow through Defrosters), the truck ran slightly better with Max AC running and would stop doing the thing where I put it in park, the engine would rev up to and idle at 2k RPM.
When I turn the AC off, however, or set it to normal, the issue returns, and the engine revs a little higher especially when put into park. No more Check Engine lights or other warnings, though.
Any advice on what I could try next? Thanks! I appreciate your time and helping me look more into this before I go and buy a whole new engine.

 

I’m a little confused about your codes. Are 121 and 565 active codes? 10 is a separator from active and stored codes and then you get 111? That means there are no stored/ continuous codes but then you say you have 172 and 332 so where did they come from?

121: test the closed and WOT voltage of the TPS sensor. What voltages do you have? Did you or someone else move the throttle stop screw? What happens to the idle when you unplug the IAC? Does the barely run or stall?

565: I don’t have pinpoint procedures to test the canister purge.

172: A vacuum leak can be big enough that the injectors are maxed out and cannot supply enough fuel. Is fuel pressure in specs?

Where is the coolant going? What did the spark plugs look like? Does it look like the engine is burning coolant? But or rent a cooling system pressure tester.

 

Thank you for your help.

These codes were pulled at separate times throughout my work, not all at once. I reran the test and corrected the codes in post above.
As of this morning, Codes 565(O), 172(C), and 332(C) appear. I think I miswrote the #10 code. It has been removed.
Let me get back to you on the rest. I'll check all of your recommendations right now.
I've had multiple people helping me out with this, so some of the stuff has been adjusted by other people, some myself, all with different advice.

 

check the ohms on the engine coolant sensor-the one under the IAC. the reading should be around 22k and drop as temp increases. Mine was climbing so it was thinking it was 30 deg so it was flooding the ***** out of it hence the sooted plugs. My o2 also had never been replaced since it was at 98k original miles. Still not as smooth as I like so I'm rebuilding a junkyard distributer since that is how to replace the magnetic pick-up.

 

Codes won't make the engine sluggish, what is the fuel pressure and what is the base timing set at?