NFL Quarterback Club'98
Speed Boost
To run faster press A for a boost. Then, instead of waiting for your meter to refill by itself, tap A repeatedly to hurry it along and allow yourself to fill up the boost meter quicker than normal. To get an even quicker speed boost push hurdle one step after you use turbo.
Credit Goes to: Chris Evans and Anthony Harness ( via IGN 64

 Speed Boost
 Always Throw
 Complete Passes

 Win Coin Toss
 Cheat Codes
Always Throw Complete Passes
Before the "hutt", hit the C-up button 5 times. This will make you throw a complete pass every time.
Credit Goes To: BOB ( via IGN 64

Always Win the Coin Toss
If you want to win the coin toss and receive the ball, all you have to do is wait until the coin is tossed and push start. When you do this your team will start heading to the bottom of the screen and you will receive.

Cheat Menu Codes
LLCHTSFF - Turn off all cheats you've entered
LWYSTPSS - Always tip the ball in the air on passes
LDSTRTRK - Instantly beam the ball to the reciever's hands
PBYBYMD - They don't run; the players crawl around.
LLDFSCK - Crappy defense
LLFFSCK - Crappy offense
YLCTRCFB - The athletes move around like an electic football game.
BGSPRDV - Super diving distance
YNSTYNS - Maximum discipline & awareness
TGHTGRP - No turnovers
SNWSLDS - Sled Mode
FRMBYFRM - Slow motion
BGTWSTRS - Ball carrier spins wildly
SPRBGRMS - Throw, kick, punt 100 yards
SPRTMMD - All attributes maximum
PWHYRMN - All attributes '0'
NBCTCKLS - Turn off tackle ball character
MNFLDMD - Up-and-over dive madness
TRNTDLFR - Quarterback accuracy 0%
GLYTHMD - Big fat players. Marv Albert's voice is sluggish and deep.
RNLDSWZNGR - Strong players & slow running backs
SMLMDGT - Tiny players. Marv's play-by-play is high-pitched.
BBMNTBL - Tall & skinny players
JPNSMWR - Short characters. Looks sort of wide and flattened
WLTRPYTN - Awesome running backs
DWNDRV - Unlimited number of downs.
MCHLJNSN - Faster players, as fast as Michael Johnson
GTNHNDS - Fumble the ball like crazy!!
SPRSLYD - Everyone is slippin' around like a bunch of fools.
STYCKYHNDS - Never drop a ball
BRDWYNMTH - Awesome Quarterbacks
CRLLWYS - Jump far
BGBFYFF - Stronger and faster players
SPRTRBMD - Players run in Turbo
8DWNDRV - 8 Down drives
STNTXTM - 2 hidden teams: Iguana and Acclaim