Need ideas Lack of power/ poor idle /exhaust sound 2.7

Ok I'll try 2 B quick here ! I have a 99 Taco 158K 2.7 I have 25K on new wires an plugs. A couple months ago it started 2 hesitate during acceleration/shifting. I have done the following cleaned throttle body, TBsenor checked @ Autozone, Inspected & didn't find any vaccume leaks, new fule filter,new air filter, injector cleaner (2 tanks) It Ran alot better but only a couple of weeks and it came back ! Not only that but now it has a rough idle and will die at stops ! So I Found TW.com since then I have cleaned the MAF sensor, connections, new battery terms., since all these attemps it still lacks power in 5th ( Cant do more than 70-75 on hwy) and it still idles bad. Now its making a cherping sound when it starts for only a few seconds then its a sssst.....ssssst .....ssssst sound from the exhaust manifold kinda sounds like a lifter knock ??? I have read a few post about cracking manifolds is this common for 1st Gen taco's ? Any ideas what I can check next

 

Well I had my tech look at it and he said he didn't have a lot of time to look at it in detail so he asked me 2 bring it back ! He did confirm that my exhaust mainfold was cracked and that something was wrong with the idle. he wanted me to come back for a compression test on friday ! I explained my sittuation with hunts and the timing i was up against ! Even if he did get all the right answers an found a major issue an could have got it fixed i will never know ! Sorry guy's But I got frustraighted and traded it in and bought an 04 Superduty ! It was only a matter of time anyway ! I haul to many toy's a boat, wheelers, & a trailer. Sorry Guys ! I really would like to have kept the truck for running but, I just got tired of working pon it !