random missfires 97 tahoe

I have a 97 chevy Tahoe with some weird problems.
Started out as a randon missfire on cylinders 6 5 and 7.
Of course we all know this is all about changing the right part to fix it, Well I haven't found it yet.
Items replaced,
All O2 sensors (5)
Complete fuek injection unit.
Fuel pump 3 times
MAF sensor twice
Map sensor twice
plugs cap rotor and wires twice
distibutor
tps switch
idle speed solonoid
complete ECM
including the ignition control module inside the ecm and it was flashed for my vin
crank sensor
new alternator
New battery and all new cables
had cats flow testyed they are good.
Flow Master mufflers flowed good.
Factory intake flows good
Last item to get changed was the ECM and the ignition control module. Random miss fire was just about gone. A miss i mean a dead miss started so i put scanner back on and it said the MAF and MAP sensors were sending erratic signals and that my EGR Valve which I aint found yet is not sending a signal. So I changed the Mak and Map sensors again (2nd time) and went to reset the codes and now the codes will not reset. I dead headed the ecm and no joy here either. When I drive the truck it smells very rich and it bucks and misses. Dead miss. I pulled plugs and all look good and of course there are new wires. I then replaced the coil itself and the ignion module next to it. Still no joy. HELP. I am approx 4400.00 dollars into this truck and I am ready to have a bion fire with it. Have replaced fuel filter three times and removed and cleaned out the fuel lines when I put on the new fuel injection unit. I also dod a compression check all cylinders 150 and staedy, Also did a leak down test with great results. HELP ME PLEASE>> I loved this truck at one time and would love to love it again.

When the erro sets, there should be freeze frame data stored with it. That information may be crucial to diagnosing the problem. Scan the PCM and retrieve the errors and data.

When the erro sets, there should be freeze frame data stored with it. That information may be crucial to diagnosing the problem. Scan the PCM and retrieve the errors and data.

I did that i dont remember the exact codes but there were six i remember what they said though
1. MAF sensor low signal
2. MAF sensor high signal
3. MAF sensor erratic signal
4. MAP sensor low signal
5. MAP sensor high signal
6. MAP sensor erratic signal

On initial scan it says all systems are okay except for the egr valve.
Saya no signal received from EGR Valve.
Went to reset codes and the scanner says codes reset and when i go to make sure codes are still there. When I try to drive it the check engine light stays steady flashing. Thnx for your quick responce. And any help you can give me in this matter. I have been dealing with this for almost a year now. And lots of money
I am at the point where my technology is not enough. Give me a small block with a regular distributer and carb and i will make it talk to you.

Check your ground wires. The EGR is about dead center at the front of the motor, should be black in color and have a connector in the top with 4 or 5 wires. I think there should be 1 or 2 ground wires connected to a stud that bolts the thermostat cover down

Check your ground wires. The EGR is about dead center at the front of the motor, should be black in color and have a connector in the top with 4 or 5 wires. I think there should be 1 or 2 ground wires connected to a stud that bolts the thermostat cover down

Tghanx for the good info. I will look at that in the morning. This thing is really buggin me.:banghead:

Exhaust restriction more than 3 psi at 200 rpm
Sticky valves....running compression test will find this

Do you have 5 volts at Pin D of the EGR valve? 12 volts at pin E?
Eng 1 fuse supplies 12v to the EGR Maf and EVAP purge solenoid
Can you jumper pin D to C and see 5volts at the VCM?

Of course we all know this is all about changing the right part to fix it, Well I haven't found it yet.

No it is not ...It is about DIAGNOSING the concern and REPAIRING the fault.
This doesn't mean that a part will fix it