So I am new to posting but regularly refer to forums for advice and troubleshooting my car issues. I have searched and searched through the forums here and over on the ecotec forums and haven't found anything similar to my issues.

I have a 2005 cavalier 2 door 5speed manual that I picked up for a couple hundred bucks planning to get back in dirt track racing by seasons end. It had timing issues and of course the usual bent valves that go with it. I took the head off got it checked out and replaced the valves, hydraulic lifters, and reinstalled with new timing kit, head gasket, head bolts, etc. Once back together, I did a compression test and all 4 cylinders are between 178-185psi. I felt confident with that so added new NGK spark plugs and fired it up. It fired right up, and sounds pretty good.

Now for the issues.... When I shift into first and let out on the clutch the engine immediately bogs and dies. I of course tried second too. Same thing. I cannot get it to gooo. Since it's going to be a dirt track racer, I wanted to put it through its paces up and down my long gravel drive, but can barely limp out of the garage. (I don't believe it is in limp mode either cause I can rev the engine clear to the limiter) Here's the weird thing though, I can put it in reverse and it goes just fine, slight bog but at least runs.

As far as troubleshooting, I started with the engine itself and here is a list of everything I have checked.
-checked plugs, gaps- plugs 1,2 are clean and slightly wet, 3,4 is slightly grey and sooty
-checked coils and ICM both seem to be good
-checked O2 and once I replaced the fuse engine light has gone off but still having same issues
-systematically replaced every sensor from a donor car on the motor to see if anything changed,nothing helped
-replaced entire intake manifold and throttle body from a donor car as well..no change
-I even swapped computers for a flashed computer from a fellow racer briefly to see if that changed anything
-checked for vacuum leaks
-replaced fuel filter and cleaned fuel injectors/fuel rail
- what else....

I had thought today that my issue could be the transmission itself...could it be and if so what specifically

Any thought or insights on what to check next would be greatly appreciated!!!! I wanna make a few races this season.