diff --git a/main.go b/main.go
index c89d734..6a80870 100644
--- a/main.go
+++ b/main.go
@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"errors"
 	"github.com/gin-gonic/gin"
-	"github.com/linux-do/tiktoken-go"
 	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
 	"golang.org/x/net/http2"
@@ -15,14 +14,9 @@ import (
 	"net/http"
 	"net/url"
 	"os"
-	"reflect"
-	"strconv"
-	"strings"
 	"time"
 )
 
-const INSTRUCT_MODEL = "gpt-3.5-turbo-instruct"
-
 type config struct {
 	Bind                 string            `json:"bind"`
 	ProxyUrl             string            `json:"proxy_url"`
@@ -31,7 +25,6 @@ type config struct {
 	CodexApiKey          string            `json:"codex_api_key"`
 	CodexApiOrganization string            `json:"codex_api_organization"`
 	CodexApiProject      string            `json:"codex_api_project"`
-	CodexMaxTokens       int               `json:"codex_max_tokens"`
 	ChatApiBase          string            `json:"chat_api_base"`
 	ChatApiKey           string            `json:"chat_api_key"`
 	ChatApiOrganization  string            `json:"chat_api_organization"`
@@ -52,43 +45,6 @@ func readConfig() *config {
 		log.Fatal(err)
 	}
 
-	v := reflect.ValueOf(_cfg).Elem()
-	t := v.Type()
-
-	for i := 0; i < v.NumField(); i++ {
-		field := v.Field(i)
-		tag := t.Field(i).Tag.Get("json")
-		if tag == "" {
-			continue
-		}
-
-		value, exists := os.LookupEnv("OVERRIDE_" + strings.ToUpper(tag))
-		if !exists {
-			continue
-		}
-
-		switch field.Kind() {
-		case reflect.String:
-			field.SetString(value)
-		case reflect.Bool:
-			if boolValue, err := strconv.ParseBool(value); err == nil {
-				field.SetBool(boolValue)
-			}
-		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-			if intValue, err := strconv.ParseInt(value, 10, 64); err == nil {
-				field.SetInt(intValue)
-			}
-		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-			if uintValue, err := strconv.ParseUint(value, 10, 64); err == nil {
-				field.SetUint(uintValue)
-			}
-		case reflect.Float32, reflect.Float64:
-			if floatValue, err := strconv.ParseFloat(value, field.Type().Bits()); err == nil {
-				field.SetFloat(floatValue)
-			}
-		}
-	}
-
 	return _cfg
 }
 
@@ -135,9 +91,8 @@ func closeIO(c io.Closer) {
 }
 
 type ProxyService struct {
-	cfg       *config
-	client    *http.Client
-	tokenizer *tiktoken.Tiktoken
+	cfg    *config
+	client *http.Client
 }
 
 func NewProxyService(cfg *config) (*ProxyService, error) {
@@ -146,15 +101,9 @@ func NewProxyService(cfg *config) (*ProxyService, error) {
 		return nil, err
 	}
 
-	tokenizer, err := tiktoken.EncodingForModel(INSTRUCT_MODEL)
-	if nil != err {
-		return nil, err
-	}
-
 	return &ProxyService{
-		cfg:       cfg,
-		client:    client,
-		tokenizer: tokenizer,
+		cfg:    cfg,
+		client: client,
 	}, nil
 }
 
@@ -242,33 +191,9 @@ func (s *ProxyService) codeCompletions(c *gin.Context) {
 		return
 	}
 
-	prompt := gjson.GetBytes(body, "prompt").String()
-	suffix := gjson.GetBytes(body, "suffix").String()
-	inputTokens := len(s.tokenizer.Encode(prompt, nil, nil))
-	suffixTokens := len(s.tokenizer.Encode(suffix, nil, nil))
-	outputTokens := int(gjson.GetBytes(body, "max_tokens").Int())
-
-	totalTokens := inputTokens + suffixTokens + outputTokens
-	if totalTokens > s.cfg.CodexMaxTokens { // reduce
-		left, right := 0, len(prompt)
-		for left < right {
-			mid := (left + right) / 2
-			subPrompt := prompt[mid:]
-			subInputTokens := len(s.tokenizer.Encode(subPrompt, nil, nil))
-			totalTokens = subInputTokens + suffixTokens + outputTokens
-			if totalTokens > s.cfg.CodexMaxTokens {
-				left = mid + 1
-			} else {
-				right = mid
-			}
-		}
-
-		body, _ = sjson.SetBytes(body, "prompt", prompt[left:])
-	}
-
 	body, _ = sjson.DeleteBytes(body, "extra")
 	body, _ = sjson.DeleteBytes(body, "nwo")
-	body, _ = sjson.SetBytes(body, "model", INSTRUCT_MODEL)
+	body, _ = sjson.SetBytes(body, "model", "gpt-3.5-turbo-instruct")
 
 	proxyUrl := s.cfg.CodexApiBase + "/completions"
 	req, err := http.NewRequestWithContext(ctx, http.MethodPost, proxyUrl, io.NopCloser(bytes.NewBuffer(body)))