my 1999 Doge Ram Sport has no power when I press on the gas, willbnot go over 3,000 RPM, whengoing up hill I loose almost all power my Check engine light stays on now but blinks when under presure

Have you had any code,s pulled from computer?From what you said about the heat sheild,s Rattaling and loss of power would lead me to think your catilac converter,s are clogged up.

You need to start by reading the code, that will narrow down the problem

I have the same exact issue but when I stepped in it again up hill testing to see whats going on my check engine light stayed on after blinking and now seems to be in a limp.mode wont go past 4200 rpm at all i lose alot of power at 3k also have same rattles. So since light is on i am throwing codes p0300 0301 0302 0304 0307 and when i went to get new plug tested again for shits and almost codes for every cylinder for misfire compression tested 1-8 at 115 psi- 160 psi 99 ram 1500 5.2 4x4

@Damon. U need to start a new trend but the 300 code means low fuel pressure. Once u fix the fuel pressure ussue yhe other codel will clear away. Ifbur not getting enough fuel, that will cause the random misfire