Need some help with my junk 3.4L

[1990BerettaGTZ2.3L]

Ok Ive had this problem for awhile well actually since I had the motor partially rebuild. Ok this was a supposed good insurance job motor that I had someone put in my 93 firebird, well after putting it in and firing it he said it had a thrown rod, so I put a new crank kit in it and new timing chain, but didn't touch cam, put new head gaskets and intake gaskets in it, ARP head and rod studs and well when my buddy fired it up he told me it had a really hard start almost too advanced for timing like but it's only when hot. Another thing is when I let off the gas at 50 mph and above check engine light comes on and it threw the code for running too lean on the right bank, and well when you get into the 3,000-4,000 rpm range it falls on it's face bad and struggles till it gets to 5k then runs good afterwards, and this motor heats up really fast and overhears what would cause this??

My guess already was a tooth off on timing chain don't know if that would cause all this crap tell me what you guys think I've changed just about every sensor, MAP, O2s, coolant sensor that tells the computer when to run lean at different temps and kick fan on when hot

[3X00-Modified]

Sounds like you got hosed with someone rebuilding your engine for you... There isn't much you can do other than take it apart and verify what was done. Do a compression check and leak down test as well to see if its a ring seal issue, but I doubt it.

[1990BerettaGTZ2.3L]

Maybe one of these weekends I'll take everything off the front of the motor and and hopefully I have a 1 piece gasket that's reusuable on the oil pan cause I'll drop the front and take off the timing cover, it's like a 2 hour job alone taking the shi* off to get to the timing cover I'll have to do it near my oiling rack out back that way when it's all off I can just pull it up on and loosen the oil pan from the underneathits way easier since my bird sits so low