[V8] "CheckEngine/Limp Mode"

[bblake1055 at aol.com]

My 17 year old got the bright idea to hose off the 90' V8 engine yesterday and now I keep getting "Check Engine" and then the "limp mode".
 
The idle jumps up and down and sometimes it will pop.  If you turn the engine off and back on it may run fine for 2 or 3 minutes and then it does it again.  He didn't really soak the engine just a light spray so it may not even be related.
 
I've got several other V8's (must be nuts) so I switched the Idle Stabilizer (didn't help) and then I switched the Air Mass Control (also no help).  I've never learned how do read the codes which I know is a must for these cars but before I go back to school on codes, is there any other easily exchange parts I can try?
 
Thanks for any help in advance
 
 
Bob Blake
 
90' V8 - Blue/Blue
91' V8 - White/Black
92' V8 - Breen/Tan
93' V8 - Blakck/Tan