I'm backfiring during free rev around ~4k rpm so bad i think the exhaust might blow off.. i think i can pass it if i rev it quick enough though. i've seen the threads with people with similar symptoms and didn't see how it was cured. I cant drive my car worth crap and ive changed my tps and map sensor and timing is right. injectors are brand new and so is fuel filter. i have the stock turbo II pump. so I dont think it's a fuel problem, how could i be going lean in free rev? would it be my spark cuting out instead?

 

backfiring is from going rich, not lean. You could be having spark problems or something could be wrong with ur fuel metering system. Possibly even a vacume leak.

 

you were right i did have a vaccum leak and stil do to a point i havent had time to track it very good but it doesnt bog anymore and is smooth through the rpms in nutral but in 2nd if i put too much load on it it cuts out sometimes but ill get it fixed