Chevrolet Repair: 99 tahoe 5.7, power brakes, mark thanks

Question
hi Mark,thanks for your input.
i have a 99 tahoe 5.7.was driving on highway uphill with a load on engine.suddenly lost engine power,and started making pinging,and rapping noise.removed rocker covers.found a loose rocker.tighened checked all others seem fine.put covers on and started,noise went away,butengine still running rough at idle and when i give it gas.removed throttlebody cover with engine running sounds like its sucking in air.drove truck back home (slowly but surely)ran very rough some deisling,and miner backfire. but also noticed power brakes not working.like no vacuum at booster pump.i'm thinking intake gasket or manifold.your thoughts would be appreciated. thanks

Answer
Hi Ramiro, I'm thing that the lifter is bad and now the lifter is pumped up and holding the valve open a little. i would recheck the lifter that you found loose. I think that the lifter colasped and you just adjusted it when the lifter was at the bottom of it's travel and now it is puimped up holding the valve open.

Let me know what you find

Hope this helps

Have a Nice Day     Mark