Problems after getting engine wet

I've posted on some other threads, but I decided to start a new one in the hopes others can offer some guidance.
Basically, I work for the USPS doing an 82-mile rural route in my 1996 S-10 with the 4.3 V6 and auto tranny. This past Thursday while trying to service some boxes out in the woods, I had the misfortune of running through some water in a deep rut which sucked water into the engine and soaked the rest of the engine compartment with muddy water. Luckily, I avoided major engine damage since I realized what had happened after it stalled out and didn't keep turning it over. I had it towed back, then proceeded to try and drain the engine. After the plugs were pulled, engine drained, plugs and wires replaced and oil drained and replaced, the engine started right up and ran smooth.
The next day on my way to work, the tranny started acting weird, though only when I got up to cruising speed (45). It shifted in and out of gear and idled rough at a stop.
Took it to an AAMCO shop (I know, big mistake after all I've read now) and they came back with six trouble codes - none of which seem to have anything to do with the tranny's hard shifting in first and other maladies.
They are:
P0103 - Mass Air Flow Sensor Circuit High Frequency
P0121 - Throttle Position Sensor A Circuit Range/Performance
P0122 - Throttle Position Sensor Circuit Low Voltage
P1106 - Map Sensor CKT Intermittant High
P1122 - Throttle Position (TP) sensor circuit intermittent low voltage
P1509 - Idle Air Control (IAC) system high RPM

I don't know what AAMCO did for the $42 diagnostic fee I was charged other than pull those codes because their bill says "After a complete external service, no transmission problem was found at this time"
Luckily I have another vehicle I can use on my route, though my 96 Beretta is not quite as roomy up front or comfortable as my truck, so I'm not in a panic rush to get this fixed. I'm just at a loss to have so many sensor failures at once. Is it possible one thing is causing all of this or am I really looking at replacing each and every one?
Any thoughts or opinions at this point are greatly appreciated.
Steve
Panama City

I've posted on some other threads, but I decided to start a new one in the hopes others can offer some guidance.
Basically, I work for the USPS doing an 82-mile rural route in my 1996 S-10 with the 4.3 V6 and auto tranny. This past Thursday while trying to service some boxes out in the woods, I had the misfortune of running through some water in a deep rut which sucked water into the engine and soaked the rest of the engine compartment with muddy water. Luckily, I avoided major engine damage since I realized what had happened after it stalled out and didn't keep turning it over. I had it towed back, then proceeded to try and drain the engine. After the plugs were pulled, engine drained, plugs and wires replaced and oil drained and replaced, the engine started right up and ran smooth.
The next day on my way to work, the tranny started acting weird, though only when I got up to cruising speed (45). It shifted in and out of gear and idled rough at a stop.
Took it to an AAMCO shop (I know, big mistake after all I've read now) and they came back with six trouble codes - none of which seem to have anything to do with the tranny's hard shifting in first and other maladies.
They are:
P0103 - Mass Air Flow Sensor Circuit High Frequency
P0121 - Throttle Position Sensor A Circuit Range/Performance
P0122 - Throttle Position Sensor Circuit Low Voltage
P1106 - Map Sensor CKT Intermittant High
P1122 - Throttle Position (TP) sensor circuit intermittent low voltage
P1509 - Idle Air Control (IAC) system high RPM

I don't know what AAMCO did for the $42 diagnostic fee I was charged other than pull those codes because their bill says "After a complete external service, no transmission problem was found at this time"
Luckily I have another vehicle I can use on my route, though my 96 Beretta is not quite as roomy up front or comfortable as my truck, so I'm not in a panic rush to get this fixed. I'm just at a loss to have so many sensor failures at once. Is it possible one thing is causing all of this or am I really looking at replacing each and every one?
Any thoughts or opinions at this point are greatly appreciated.
Steve
Panama City
IT IS POSSIBLE THAT ONE THING IS CAUSING ALL YOUR SENSOR TO GO BONKERS:WATER. SOME WATER MIGHT HAVE GOTTEN INTO THE WIRING AND NOW YOUR SENSORS ARE SCREWY.

Wild guess, air getting into the engine after the mass air flow sensor, cracked or loose air inlet hose? Did you check the air box and air cleaner?

The MAP sensor and the TPS sensor have everything to do with the transmission. The PCM uses these plus several others to calculate shift points and in some vehicles, shift firmness..

Wild guess, air getting into the engine after the mass air flow sensor, cracked or loose air inlet hose? Did you check the air box and air cleaner?

Before the incident, I had one of those K&N air filters on, which was nothing more than a bent pipe with the cone air filter at the end. This, I think, exacerbated the problem of getting water into the engine. I have since taken that off and replaced it with the original bulky air box and filter since the air inlet is somewhat smaller and there is a drain hole on the bottom of the box if water got in it. Maybe it's a bit loose and I'll mention that to the shop I'm taking it to.
I went to pick up the truck from the AAMCO lot last night to take it to another private shop, but all it did was turn over, never catching, making me think they had screwed something up.
Turns out they just ran the thing completely out of gas. After making two trips with a gas can, it fired right up. Whew!
Hopefully this other place will be able to get the thing fixed in short order and be back delivering mail out in the boonies in no time.

After taking the advice of taking my truck to a local guy, it's back up and running. Diagnosed with a bad TPS sensor and Idle Control. Took both off, and each still had water in them. Idle sensor actually had the start of some rust while the TPS was immovable.
Once replaced, truck runs fine, shifts fine, sounds good and Check Engine light has not come back on. I'll be using it Saturday on my postal route, so I'll feel more confident that it's back up to speed once that long day is over.
Great thing - actually cost me less for this fix than the other place was going to charge just to diagnose the problems. I know where I'll be taking my truck back for future work, but here's hoping I don't have to be doing that much in the future.
Thanks to everyone for their advice and hopefully if someone goes through this type of situation in the future, they'll know what to key on.