Running good to running bad ( back and forth )

[dram]

I have a 1992 V6 Forerunner that is driving me crazier ! Problem is it will run great for maybe 50 miles and then next 50 it will sputter , miss, backfire , lose power and sometimes die . I have tried plug ,wires , gas filter , and even trip to local Toyota dealer($260) . Supposedly it was grounded wire ion engine . Same old thing ran great 100 mile and started missing , backfiring , sputtering etc . Does not matter whether engine is c old or hot . Is it possible for this to be water in my gas . It does run like that .I just do not know . Any help would be greatly appreciated . Ibougt this vehicle from a friend 3 years ago (and 30 K miles ago ) with no problems until now . It has 160K on it .

[kuto]

check your ignition coil and change the plugs

[dram]

Just in case it may help someone in the future , I got my 92 forerunner run good run bad problem I posted fixed . It turned out to be the fuel pump . Don't ask me how pump could be problem with it running from good to bad . Looks like it would be bad constantly , but it wasn't . Hope trhis helps someone on down the road .