Doesn't idle, hesitated, codes 14,21,45,53

[C-mo45]

Hi, I saw your webpage and have been using it to help guide me in fixing my 1993 Suzuki sidekick. Lately its been idling really weird, it will either idle around 1500 rpm or it will just drop down to about nothing and wanna just stall out on me. When you take it down the road it will hesitate really bad and you can hardly get it over 30mph. I've also noticed its running extremely rich and I am getting only 15 mpgs. Ive replaced and check numerous different things and nothing has seemed to help. Here is the list of things I've done:
New fuel pump, tank, fuel filter
pcv valve
air filter
ECT sensor
TPS sensor ( new and was calibrated)
New spark plugs
Distributor and cap
New timing belt
replaced Egr gasket
replaced throttle body gasket
cleaned the ISC
cleaned IAC
On top of that I am still getting codes 14, 45, 53, and 21. Once again I have a 1993 suzuki sidekick jx 16 valve. I would greatly appreciate any advice or tips you could give as you seem to be an expert on these old suzukis. Thank you! R